Log into your account on your phone and it will automatically show you the offers available in your area. Tap on the offer you wish to redeem listed under "Today" in order to see the details of the offer. When visiting the venue, present this offer and they will tap through it. Be ready to show some ID if they ask for it! After they've tapped through, you're good to go!
Instructions on your GetOutPass will arrive via email immediately after purchase.
This video will help you understand how to best use the GetOutPass: https://www.youtube.com/watch?v=kpG6bOoMueY