It's super simple!
1. Collect all the Coke codes you can (You can also enter one at a time.)
2. Create your Mycokerewards acct by visiting MyCokeRewards
3. Enter your codes to collect them up and redeem for great prizes!
Their prizes change from time to time and some are in short supply, so check back often!
Here are a few of the magazine subscriptions that I have received personally for free with my coke rewards...