Register - register a new domain that does not exist.
Transfer - transfer an existing domain with an EPP-code. (this could potentially be dangerous if done too early)
Use Existing - choose a primary domain to be set up for your account. This does not affect your current website but instead prepares the account with the chosen domain so you can start building the website and afterward point it to our servers.
Use Subdomain - create a free subdomain with hemsida.eu if you want a domain to visit or if you do not have any other domains, or do not want to tie an important domain as the primary domain on the account. (the primary domain cannot be changed later on, we always recommend to choose this option to grant you more flexibility)