The Apple Help file says:
To see your current computer name, Local Hostname, or network address, open the Sharing pane of System Preferences.
To change your computer's name, type a new name in the Computer Name field.
To change your computer's Local Hostname, click Edit and type a new name.
To see the address of the services you are providing, select the service. The address is displayed below the Services window.
I'm pretty sure I clicked to register at a later date... Anyway I'm wondering, how can I get back to that form and change my information? Also, how do I submit it now that I'm ready to?
If you didn't want Apple to have it but have gone online with that computer, Apple probably has it.
There's an alias to the file containing the info called Register or Registration, if I recall correctly, visible as soon as you click the hard-drive icon or inside one of the top-level folders.
If it's not there, run a search for
to cover the possibility it's named Register or Registration.
You might not find the alias or the file because both might disappear on their own if the connection to Apple got through. I don't know if you can change that info if it hasn't, but you could trash the alias and the original.