In the School/Ages menu:

We can establish different ages and then assign them to the courses of our School and depending on their age we will know to which group we can assign them. 

     1. Choose New.
     2. Fill in the Name field the age or age range we want to create.
     3. Save.

In this way we have created a list with the different age ranges that we have established that we can then include, within the Ages of Courses tab.