How this work?

Here.

tl;dr you create giveaways for games you like to gift and/or enter giveaways for a chance to win that certain game.

You join over 9000 private groups with group giveaways with all your accounts and enter group giveaways. If you need to pass some contribution level, you just create giveaways with bundle games or giveaway to you other accounts. That easy!