To close a question you have to mark a post as the solution.

Just post good things, nothing about dead people or goats:)

The First Rule of the Rep Club: do not talk about the Rep Club.
The Second Rule of the Rep Club: DO NOT TALK about the Rep Club :)
Other than that, just hang around, be nice and constructive, don't act like an ass, if you have a nice idea for a competition and want to share some games you like (or hate... :)) with others - run a giveaway.
To close a question - move your mouse over the post that contains the solution to your problem and you'll see a button with green star and 'Mark as solution' - click it and the question will be marked as answered.

+1 rep per day of posting
+5 rep for posting a solution to a question
up to 5 (may be 6) rep per day for an uprated post, no known limit

lose up to 5 rep per day for a downrated post, again no known limit.

Best way to increase your rep is to ignore it, and check it again after a couple of months. Assuming you do participate in the community, rep should naturally rise.

First rule about the rep: Don't talk about the rep!

Serious answer: You get 1 rep point everyday you post something in the forum. You get 5 rep points if a post of you is marked as solution in a question-thread. You can gain up to 5 points per day if you posts get a positive rating and you can loose up to five points if they get a negative rating.

So become an active part of the community, be nice to everyone, if you can afford, do a giveaway once in a while and your rep will go up in a short time.

Edit: Double ninja'd...

Go to the subforums of games that you know stuff about, then answer questions, post hints and stuff. Avoid general discussion.

Don't beg for games and it will come on its own.

Have a large penis.

Rep is the local equivalent of "[url=http://en.wikipedia.org/wiki/The_Game_(mind_game)]the game[/url]" (by the way, i lost).

You have to sacrifice a chicken while dancing naked around a fire during a new moon and give offerings (Vodka) to the guys in blue.

Did someone say penis?

Bloody great, you made me loose now.

And now you will every time someone mentions rep. :-(

you get rep by not creating few topics asking for games from other users