Admins need to add students to Classes. They may do this when students move classes during the year. This process is not suitable when adding a new student to your school - follow link.
Step 1: Click on the Classes (left-hand menu)
Step 2: Locate the required Class.
Step 3: Click on Manage Students below the Actions column:
Step 4: Choose ADD STUDENTS from the right hand-side of the screen.
Step 5: Select the student, or multiple learners, and CLICK Add Students
Students will be added to that class.