Navigate to 'Settings' --> 'Role Management' and press 'Create Role'. 

(Or choose to edit an existing role)

Create a 'Role Name'.

To set permissions, click on a role.

Click on a question mark in order to get an explanation of the permission. The box must be clicked to activate the permission.

Make sure you save all changes.
Press 'Save Changes'.

Navigate to the right tab ('Users') in order to see which users belong to a team role.