How to contribute?

You ask a lot.
Go FAQ yourself.

Long story short, to contribute you must create a giveaway for a game that you own an unused copy of it (NOT IN LIBRARY) but in inventory or a Key.
Oh btw being active on forum, be polite (like me) and etc is also a contribution. At least in this place.

Yup, give games m8. And I haven't seen any people who have contributed 0.01, can I have a link to a profile with that? Or are you just talking about the minimum contribution value to enter a giveaway?

Yeah Im just talking about the minimum value to enter. After reading the FAQ, I understand it better now. Thanks guys :)

First, read the entire FAQ. That will probably answer most of the questions you have. Second, only create a giveaway if you have a gift copy or an unused Steam key for the game that you are willing to give away. You can't give away games in your Steam library. Third, I don't think anyone can contribute just $0.01. What you are seeing is a contribution requirement for giveaways. To enter those, you must have given away that value in games (note: bundled games don't always give full value). Most people just set a contributor requirement of $0.01 to allow anyone who has at least contributed one game.

EDIT: Looks like you've read the FAQ already and figured things out. Welcome to the site!