If i win a game is there an email to my adress or something (how can i see it)

Green bar on every page saying you've won a giveaway.

It will be shown in a green box on this site.

You will see a giant green banner on the steam gifts site. You will also get an email from the user you won from if they decide to email you the gift.

So you have to regularly visit the site if you want to know it as soon as possible.
If someone randomly adds you on Steam, you should instantly load up Steamgifts.com and check if you won something.

I'm not sure what you're asking about, so I'll cover both possibilities.

You know you won when you see the green bar others mentioned.

Whoever made a giveaway receives a link to your Steam profile and e-mail so he can send the game.

thx you very much