The name pretty much says it all ... Second Life. Yes, to some degree it IS a big virtual chatroom, but it's a lot more than that too.
You create an avatar that becomes the representation of you in Second Life (I'll just call it SL from now on). Initially you are restricted to one of 5 or 6 avatar options as you join SL and each has a male or female version.
When you begin, you go through an Orientation Island followed by an area called Help Island. In the first you learn some basic SL mechanics and in the second you can pick up some free items to start you off in SL.
Next you go to the very crowded place someone else here mentioned. This is called the Aherne Infohub and it's the usual starting point for most English-speaking SL residents. As 'new arrivals' are teleporting here all the time, it gets very packed. Some SL residents like to impress the 'newbies' with their cool avies - other veterans hang out here to offer help to new players. Others are here to try to recruit innocent newbies into scam schemes. My advice is to not accept anything anyone tries to give you in this area.
After this, the virtual world is your oyster. Of course, at this point you will have no idea what is going on or what you are supposed to do. Search is a great tool though. Go into the Search window and type any of the following:
Freedove
Yadni's Junkyard
Freebie Island
NCI Plazza
These are just 4 places that have loads of freebies.
To make your avatar look better (girls especially) go to the following places for freebies:
Maitraya (a pair of nice black stilettos in a bag on a bench outside the store)
Icing (Three really nice dresses in the corner of the store)
Sin Skin (pack of very nice skins for residents under 30 days old)
Fleur (another pack of nice skins for 30 days or younger residents)
Zero Style (2 packs of hair on a table to the left as you enter the store)
Tami McCoy (a free hairstyle of your choice if 30 days or younger)
GuRL6 (more hair for under 30 days old)
Muse (often has free jewellery packs)
OK, so you have some nice stuff for your avatar to wear and now you need something to do. Well, search is going to come in handy again. Think about the things you enjoy. Do you like dance clubs? Try typing that in. If you wish narrow the search. Say you like jazz, try typing in 'Jazz Clubs'. Want live music? Narrow the search to events and type in 'Live Music'. you will be amazed at what comes up.
Let's say your passion is shopping. You can do that too. From wandering around to get your freebies, you will have seen lots of clothes, hair, eyes, shoes, skins and accessories all for sale. To buy these non-freebie items, you need money. This is quite simple to do. You go to the SL wewbsite and log in using your normal SL name and password, then go to your account. Here you need to upgrade from the totally freebie account to adding credit card details. You're not signing up for a paid account here. All you are doing is allowing yourself to buy SL money in-world. RIght now, you don't need a premium account - so ignore that option. If at any time you want to remove your card details, you can.
Now, back in SL, you will see a little pale blue square at the top of the screen with the characters 'L$' on it. Click on this and you can purchase money in SL. It tells you how much in US$ the transaction will be. You will see you get a lot of L$s for a few US$s. Don't worry about overspending. For the first few weeks, SL limits the amount of L$s you can buy so you get a feel for the whole thing without going crazy. This infuriates some people, but it really is a good idea as it kind of conditions you into being a sensible buyer.
Now you look good and you have money in your virtual purse.
As you go to places you will meet people. Some will not be nice, others may become great friends. People will tell you about various things happening in SL. In a short space of time, you may - just as in real life - find a cirlce of friends and all frequent the same locations in SL, such as a club or live music venue. There may be a role-playing group that grabs your interest, such as vampires, steampunk, star wars or fantasy. You might decide that your SL avatar is going to be a demon or an angel, a punk, a Goth, a Lord of the Rings type hero or even an animal of some sort. You may even decide that you want to experience your second life as a member of the opposite sex.
The fact is, you can be anything you want to be and very few people - if any - will judge you for the choices you make, as long as you respect other people.
There are some very popular character types, groups and interests in SL. There is a huge furry community. On the fringe of this is the neko community (half cat - half human) and that society is truly vast. There are gay communities/groups, Christian communities/groups and many disabled groups. In fact, you propably not realise initially how many of the people you befriend in SL are disabled in real life (rl) to the point that they are totally housebound and SL is their only outlet to express themselves and socialise. One of the biggest groups in SL is the Relay For Life group which is a monumental cancer charity and fundraiser. It is a truly global charity raising milions of real dollars to go towards cancer research. Unlike so many other cancer charities, this charity is not faceless. Many people in SL are cancer fighters or survivors.
After a while in SL, you will almost certainly be asked to go on a date with someone. Dates in SL are as varied as rl dates and with as many successes and failures. How far can an SL date go? As far as a real life date. Yes - there is sex in SL. At first, the thought of virtual sex may sound very silly, but it is a very popular SL pastime. Like in rl, dates can be a one-night stand or can blossem into a deep, loving relationship. You can even get married in SL, although this marriage is not legally binding in rl.
If you really take to SL you will almost certainly want an in-world home base. As you signed up for SL, you will be given the impression that you need a premium (monthly paid) account to buy virtual land. This is not the case at all. There are two types of land you can buy: Linden Land/Linden Island or Private land. Linden land is situated on the mainland - or huge landmass areas. Alternatively (if you have real life money to burn) you can buy your own island from Linden Labs. One of the great things about islands is that they can be divided up into smaller parcels and sold on to anyone, as long as they can pay the cost of the land and the monthly tier (think of this as a sort of land tax). Parcels come in many sizes so you can start out with something small and buy a bigger parcel if you want it later on. You can make it so only you and selected friends can enter your area of land. Then you need a house on your land. You can buy one, or you can make one.
As you learn building skills in SL, you can sell what you make. You need a place to sell your goods. You can rent space in a mall, or buy land and build a store. In time, SL can pay for itself if you are making things people want and the fact is people are spending thousands and thousands of dollars every day in SL. Eventually, you could make enough to earn a rl living wage, but what you sell needs to have mass appeal and be of very good quality.
Really, I have only scratched the surface on every single aspect of SL I have mentioned here. I could write the length of this answer on each subject and still only be telling you a tiny bit about them. The person who got fed up at Aherne felt that way because he didn't know what to do next.That is quite understandable because it's all very confusing for newcomers. There are no rules in SL and most things don't happen automatically after a set time. COmputer games condition us to wait for the challenge and then go and do it before the next one presents itself. In SL, you have to create your own challenges most of the time. That's not an easy thing for most folks to get their head round. In SL, you stick with it. You explore. You ask questions. You learn. In much the same way as if you open your Internet browser and just wait for it to entertain you without actually doing anything, if you just wait for something to happen in SL, you'll be standing there for a very long time.
My final bit of advice is to befriend a fellow newbie as soon as you can - a few if possible. Explore things together and learn together. You will both be at the same level of understanding as you set out in SL. You will sometimes feel foolish when you make a mistake, but remember that everyone in SL started out as a newbie once. When you both make mistakes you will laugh about it. When you learn something new you will share the experience. And you certainly won't feel so lost or lonely in your first few days in SL.