New Users can be added through the Web Portal > Users > New User to add a new user to your account. 

You will then need to select a User Type, enter the User's name (this is what will show up when using User Variables or Placeholders), email address, Username (this must have no spaces or unusual characters), and a temporary password.

Next, you will need to select the User Group(s) that the User is assigned to and enter any other details that are relevant. Finally, click Save. The new user will have their login details sent to the nominated email address and will be able to log in right away and access the areas that they have User Permissions for.