You can sign up using an account from:
/user/123-

Use a uniquely identifying name for you. This will also help you to be found in the search. Use only letters, numbers and underlines, from 4 to 30 chars.

Use at least 6 chars here. Preferably, with numbers and letters! Bonus points if you include lower-case and upper-case letters, as well as symbols.

Just to be sure there's no typo, could you please repeat that password?