Whee! I've done my first bit of system administration, namely on myself (or rather, on my laptop). There was a typo in my username.
To remedy, you can't simply go and rename yourself. But it wasn't a lot harder than that, since my account has admin rights.
- Apple menu -> System Preferences -> Users and groups
- Create a new user by clicking the +
- Give the user admin rights
- Log off
- Log in as your newly created admin user
- Open a Terminal (F4 -> type "term")
- cd ..
- mv wrongname username
- As above, open open and unlock Users and groups
- Rename your old account's full name
- Create a new user with your name and the right username
- Delete your old account
- Log off and log in as yourself
- Delete the temporary admin account