I'm not the coordinating teacher at my school. How can I add licences for the Class Activities or modify the Contest registration?

You will have to be assigned the "admin" role by the coordinating teacher of your school. 

The coordinating teacher of your school will have to log into his or her account and:

1- Search your name in his/her "Colleagues" list

2- Click on your name

3- Click on "Change role" on the right-hand-side corner

4- Assign you the "admin" role 

By following these steps, you will have the same rights as the coordinating teacher of your school.