I'll try to guide you through the GungHO ID creation, at least.
Before you start though, you will need to be able to type in some Japanese (or at least find some to copy and paste).
First, go to the register
The first field is for your ID. Just type in whatever you want your ID to be (4-10 characters). Note that, although they have @sun in the example, and if you follow the link, they'll give other star examples (@mon, @mcy), you should not enter in one of your own. It will be assigned to you when your account is created (incidentally, I got Moon/@mon).
The second and third fields are for your password. It must be alphanumeric, 8-16 characters.
The next two are your surname and given name, assumedly in kanji.
The two just below those are your surname and given name in furigana (the kana equivalent of your name).
The next field is for your nickname. Either English or Japanese will work, 4-16 characters. There's a button next to the field to test whether or not the name has already been taken. If it reads your_nickname & "ã