Choose how to add someone
Everyone who works on a project needs their own account. Open Project Settings → Users → User List and select the add-user icon at the top right. The Options window offers three ways to bring someone in — pick the one that fits, then select Continue:
Add User — you create the account and set the person's name, username, and password yourself. Best for field teams who don't manage their own sign-up — and important when your team doesn't have email addresses, since it's the only way in that needs none.
Send Invitation — you email an invitation and the person sets up their own account. Best when people have email.
Assign Role — the person already has a Zite account (perhaps on another project in your team); you just give them a role here.
Whichever you choose, the last step is the same: choosing the person's role and scope. That's covered in Assign a role & set scope.
(Managing people who are already on the project — editing details, changing access, removing someone — is covered in The User List.)