Join the Indie Gala steam group, then head on over to the Indie Gala website[www.indiegala.com]. Scroll down and enter your e-mail as well as a recaptcha. You should then get sent a e-mail containing a link to your account, click on it. On the website put the game into your steam library by signing into your steam account and clicking on the button (you can gift it by clicking the gift button).

AND YOU'RE DONE!!!