How can i send a gift to someone?

You can NOT send a game from your library as a gift. You should have an extra copy or buy it as a gift from the very beginning.

Edit: Guess your 2 giveaways aren't legit then.

It is not possible. Steam does not allow that, it's a form to prevent all sorts of scamming and account hijacking problems.

Oh..if i knew it i wouldn't opened a Giveaway.
I'll try to explain to the winner that there was a mistake and i didn't knew it.

Reading FAQ before posting a giveaway to evade inconveniences.

Sure thing, will do.
Thanks guys.

You have to own the game like a gift to be able to gift it like a gift. Not a difficult concept. Should have at least asked before creating two giveaways.

Just wanted to do something nice. and i got it already, but thanks anyway.