CritterCoin allows synchronizing teachers and students with your ClassLink service. First you must configure ClassLink to allow CritterCoin to access your data. Follow the instructions in the CritterCoin ClassLink Guide to get started.
Once configured you can manually sync your ClassLink data in the Students and Teacher sections in the Admin site.
TIP: There is an admin option in the Settings section that will allow you to automatically sync your teacher and student data every day.