Urgent! How to copy an instance?

Hi,

I have an instance A and want to have an instance B which is an exact copy of A. When I copy all the data and control files to a new location where do I have to make changes in instance B to use the new (copied) datafiles. I have to avoid instance B using the datafiles of A.
I need help because all this has to be done during the next 3 houres (that's why I don't have the time to RTFM).

Thank you in advance,

Knut

-- 
Knut Lassmann        myToys.de GmbH       +49-30-72 62 01 411
        I had joy, I had fun, I had Pacman on a SUN(E3500).