Registering for Rock Band on the MVEIM site can be confusing. Hopefully these steps will help.
1. Log on to MVEIM
2. Select Register for Class
3. Select CCO's Mountain Vista Elementary Instrumental Music
4. Select "view" next to Mountain Vista
5. Under "Session Type", select Sand Creek.
6. Scroll down until you find the class you want. The Select Rock Band is available by audition.