Go to Customers & Partners / CSA Members / Add Subscriber.
Enter the member info, a new Subscriber record will be created.
To invite the member to create a log-in, click on the member name and then the Send Login Account Invite. An e-mail will be sent to the member with a link allowing them to create a password, and view their Member Dashboard.
To add a CSA subscription to a new member see Adding Subscriptions Manually.