If you do not see the Permissions tab on the left, you will need to get a System Administrator to turn this option on for you.
System Administrators Guide
To turn on Permissions, Hover over the Cog Wheel, select System Settings, and it will open up System Roles
Edit the Role the staff member is in
Tick all the boxes under the Permissions option:
Once modified to your needs, select save.
This should then allow all staff members within the System Role specified to have access to the Permissions tab on the left-hand side menu.