Don't win point after a completly giveaway ?

No, you don't get points. You get Contribution Value, which allows you to enter certain giveaways.

Nope, you don't get points this isn't GameMiner. You do however get Contribution Value (CV) which allows you to enter giveaways that have certain CV requirements. Price of the game = Contribution Value in 1:1 ratio.

Ah thanks you guys and where i see those contribution point ?

http://www.steamgifts.com/user/Darsys right side

Thanks you ^^ just a last question , when i participate to giveaway with contribution value like 5$ , i lose 5$ or not ?

nope

ok thx for answer :) , i close the topic