You will use your email address to login.

You only need to enter a profile address name only (e.g. janesmith, or bobsmith etc.) - this will be alphanumeric (i.e. letters and number only) with NO spaces - and this will be used at the end of your profile link, so you will be able to access your profile directly using
http://www.transtastic.com/se4/profile/yourname after you have created your profile.