Spaces are allowed; punctuation is not allowed except for periods, hyphens, and underscores.

A valid e-mail address. All e-mails from the system will be sent to this address. The e-mail address is not made public and will only be used if you wish to receive a new password or wish to receive certain news or notifications by e-mail.

Your virtual face or picture. Maximum dimensions are 100x100 and the maximum size is 35 kB. Your picture will be resized by the site so you shouldn't need to worry too much about that. If you have a particularly large file you may want to edit it down before you make it your profile picture because it will take a long time to process and upload.