Once you've uploaded your students, you need to organise them into classes on the Class Admin page.
Add a Class by clicking "Create Class" from the Class List on the left. Enter the details and ensure you pick the correct Academic Year. This will create an empty class. Once you've selected a Class in the Class List, you can add or remove students using the check boxes.
The fastest way to organise your classes is to click the 'Assign Class by Registration Form' button. This automatically creates classes and adds learners based on the 'Registration Form' field in the learner record.