After selecting the "Client" tab in the Settings page, select the "Client Lookup" tab.

Select the client you want to invite by entering the client's name, primary e-mail address, or telephone number in the search field or by finding the client in the list; once you have found the client, select "View Details" next to the appropriate client name.

In the Client Details section, click on the "Send Invitation" link to send an automated email to the client with information about using the system.