You must register as a Hirðmaðr upon successful completion of your Hirðmaðr - Víkingr Trainee (Level 1) course, and only after you have been instructed to do so by a Úlfheðinn.
The information provided will be used to mail you your unit patch, and to email you your completion paperwork. Your first and last name, email address, and country, as provided, will also be entered in the Hirðmenn and Víkingaherr (The Víkinga Order) registry. Your personal address, phone number, and date of birth will not be made public and will be stored in Iceland, beyond the reach of U.S. and European courts.
And yeah, the photo of the dude freezing his ass off is one of the many things you should start looking forward to if you are selected for further training.