Can i activate the games from Humble Indie Bundle 7 in steam?

As long as you paid over $1 you will get Steam keys.

There should be a button- "Click here for your Steam-redeemable keys" or something.

Yes unless you paid under a dollar.

Yes you can.
Go to the your Humble indie Bundle 7 key page and click "Click here for Steam keys" or something like that.
Edit: Ah, forgot you needed to pay a dollar.

On the bottom of the page click on the bundle you want the keys from. Then click on "Click here for your Steam keys." Follow the steps and enjoy your game.

Did you pay less than an euro?

You should be have been provided with Steam keys if you paid over the average price on the Humble Bundle. If you paid under it, you won't be get the keys, I think.

Thank You all guys ;)