How to? Locate the "Giveaway teaser" on Indie Gala's website. Enter your mail there and wait for the confirm mail. After you've received the email, just login in at Indie Gala and grab the Steam key from your profile page. Have fun. You should receive an email from Indie Gala within 60 - 120 minutes. The redeem-link for this game will appear on your Indie Gala profile page after some minutes. Sometimes it takes a little bit longer. Please be patient.
If you've any question or problem, then just take a look at the comments! Feel free to ask a question, or just add a note!