You can add users one at a time, or bulk upload using a csv file. LGfL offer a USO sync so that you don't have to manage users as they are automatically added from your MIS/AD.
If your school is using LGfL USO sync, your organisational units will be synced with your active directory structure so there's no need for you to manage anything! If you are managing your users yourselves, then below are some recommended structures to help manage your users.
Your organisation structure is really important as it allows you to configure different settings for your users elsewhere in the Admin console. Be aware that your organisation units are not mailing lists and you should use Groups for this purpose.
We do have a free tool that allows you to sync your OU structure with Google Groups. You can get it for free here.
When you click on a user, you can do a variety of useful tasks: