2 Ways to do this
First Way:
Teachers > CMS Classroom Management > CMS Classroom Management
Click Roster
Click the Add Registration Button
Fill out the Necessary Information to pull the list of students
Click Search
Select the Students you want to enroll in the class
Click Registar Selected
If all the information on this screens looks correct
Click Register Students
Second Way:
Classes > Classroom -Based > List Classes
Click the Enrollment Numbers
Click the Plus Sign
Fill out the Necessary Information to pull the list of students
Click Search
Select the Students you want to enroll in the class
Click Registar Selected
If all the information on this screens looks correct
Click Register Students