I've already backed Blocks personally, but now they're doing this thing where you can get extra modules for free once you've backed the Kickstarter campaign.
I'm not entirely sure how it works, but if you've backed the Kickstarter, then you go here (my page) and get credits.
So, if you've already backed their kickstarter, then go here and do what it says. If you haven't and were planning to back the kickstarter, then do that first, then go here. Make sense?