Creating a new user is a permission reserved only for Organisation Admin and Project Admin users. If you need a new user account created, you'll need to contact your Project's Admin or Organisation's Admin to create it.
Step 1: From within the Admin area, click 'Users'.
Step 2: Click 'Add User'
Step 3: Enter new user's details in the 'Add User' form.
Note: All New User's are created with the permission 'Standard User'. User's permissions can be updated to Project Admin by these steps. Organisation Admin's can only be assigned by the Organisation's Admin or Mastt.