You can't and you should not create a new account if you're already banned.
That's bullshit.
You can appeal your ban, for which you need another account, obviously.
As long as you don't evade you ban, which will result in a lot longer one, that's ok.
You're only allowed to post in the Meta section, and only in regard to the appeal of your own ban.
Nobody will be abled to help you without knowing the account, the reason and the duration of your ban.