To change your class name;
1) Select Settings at the top
2) Click MANAGE in the Manage students box
3) Find the class you would like to change and click View details
4) Change the class name and Save
Each class name can only be used once. This is done to avoid confusion should you want to upload the students via a spreadsheet or are trying to set activities.
If you are teaching the same class of students in the following year you rather then creating a new class you can simply rename your existing class.