About the worst thing you can do to a windows XP network, especially an XP pro network, is run the wizards. So much so that now that it's hosed it may be irreperably damaged. Probably not though. As VHockey86 is inquiring, define what your intent is and how your setup currently. Setting up an IP network on XP pro is about as easy a thing you can do on a windows network. Assign IP's, name your workgroup on each PC, share your resources and setup user accounts. Not much else to it. If your trying to use ICS and share an internet connection your IP scheme will be setup automatically.
P.S. You say you don't know how to setup XP manually. That is why google is such a great tool. You'll only get a few hundred walkthroughs if you google setting up XP network