You should use a user from your domain.
Find a application that you wish to publish, when you publish it, you will add a Group form you Active Directory. Find a user that is part of that group and log him in. You can make a test group, and a test user that is part of that group.
When setting up a citrix server/farm you need to know how to work in the AD. It will save you a lot of time and troubles to hook up with one that know how set the Architecture up.