The permissions screen is where you allow users to access ticket categories as "owners", manage access to assets and billing, and also add additional site administrators.
System Permissions
The top section is where you can give users access to assets, billing, or full site administration. Each permission has a "Read" or "Edit" option. If someone only has "Read" permissions to something ,all editable fields and associated buttons will be read only or hidden.
Global admin gives users the same access as your initial admin user, which is everything. Also your initial admin user is in this list and this user can not be removed or altered.
Asset admin gives users access to assets, inventory, contracts, and POs.
Billing admin gives users access to billing, and the ability to change or cancel the subscription if set to "Edit"
Department Permissions
This section lists all departments in your help desk. In order to allow users to handle tickets in those departments, they need to have "edit" permissions in those department(s). If someone just has "read" permissions, they won't be able to process/handle tickets, but they can open them and read all details.
Managing Users
With any permission, you can add users by searching for them, remove them by clicking the X icon by their name, or switch their permission type by using the radio buttons.