In order to create an account, you'll need to register with a current email address, so your account can be confirmed. Your user name will either be your email address or a name you select. You'll be able to choose a password for your account.
Some sites allow job seekers to register with their Facebook or LinkedIn information. On those sites, you'll able to use your Facebook or LinkedIn user name and password to access the site. You may also be able to import your employment history from the site you use to connect.