To add new users to your account first navigate to Configuration > Users & Permissions > Users.  A summary table of all current users on the system will be displayed, you can view and edit user details here.

Add a new User by clicking on the New (+) button. A Person record is required first and then their User details can be completed.  You will be able to select an existing Person record from the system by clicking the magnifying glass icon in the Person field, or, if the Person record does not exist you can create a new one by clicking + from the same field and filling out the relevant name and contact fields.  

User Login Details such as Username, Password, Start-Date and End-Date can be entered in the User Details section.

Fig 1 New User

Also in the User Details section it is possible to set Seated User and Administrator privileges.The Administrator checkbox allows the User access to the Configuration section to change system settings. This will normally only apply to project managers.

A Seated User is a current user of the system who can log in, edit etc.  Users cannot be Deleted or Archived, If a user no longer needs access to the system they can be un-seated. Un-seated users do not count towards your plans limit for total users. This allows you to remove an unneeded user whilst still retaining the user on record.  

Default security groups can also be set in the Defaults section, setting which security groups are added to each entity created by default, click here for more details.

A supervisor for Approval processing can be set for each user in the 'My Supervisor is' option, use the search function to assign a Supervisor for the User.  A Supervisor is required if the account has the Approvals feature switched on and the option 'Allow user to submit for approval using Supervisor Hierarchy' is switched on then this field is required to define who the Approval request is to be sent to.