If you have a wireless computer do you need to have a router to hook up to a printer if it is the second computer connected to it?

If the printer is connected to another computer via a cable, then you need something for the wireless computer to connect to. It would either have to connect to a wireless router or you could have a wireless card in the other computer and configure the two to talk to each other. But using a router is a far better solution. Then you can setup the printer as shared from the first computer and configure the two comptuers to be in the same workgroup and share it that way.