In the Help & site information section:
Hello
Let's get you signed up:Tips
• The username you choose will be visible to other people when you post messages; you might want to use a nickname rather than something that reveals your real name.
• Usernames can only consist of lower-case letters and numbers - no spaces or punctuation.
• You must not choose a username that might cause offence, nor one that implies that you represent an organisation, business or other third party, unless with their consent.
• We won't give your details to anyone else without your permission. We don't share or sell our list of users.
