wireless networking

I need to set up a wireless Peer to Peer network with 4 computers. Two laptops 1 windows xp and 1 Mac. Two desktop pc’s 1 windows xp and 1 windows 98. All the equipment is waiting for me I just need to set everything up to share printer and DSL internet connection. I have never set up a wireless network before and I am not sure how to do this. Can anyone give me some direction?