How do I add other users?

You can add users by going to Settings > Workspace Settings > Invite a new user.

Enter the email address of the person you want to add in the [Invite a new user] field and click the [Invite] button. This will send an invitation email to the email address you entered.
The invitation email is valid for 30 days.

There is no limit to the number of users you can invite, and there are no domain restrictions.