Before adding staff users, please setup user roles first here: https://gigzph.org/knowledge-base/article/pms-how-to-add-user-roles
Back to adding staff users.
On dashboard, go to SETUP>STAFF and click NEW STAFF MEMBER.
Fill up user Profile.
If the user is an administrator, check Administrator at the bottom. The Administrator role has the power to delete other administrators, so it might be better to leave this unchecked for most users. Set a temporary password.
Click Permissions. Choose the Role for the new user. You can additionally customize the new user's permission by checking or unchecking individual features. Click SAVE when done.