First, check the documentation that came with your printer to determine how it’s designed to connect to computers. Connections made through Ethernet, USB and (obsolescent) parallel ports are common, but newer printers are sometimes wireless-enabled and allow you to simply add them to your wireless network.
Refer to the owner’s manual for your particular wireless router. Inside, find the default IP address and the default login info. If you own a Linksys router, the IP address is usually 192.168.1.1. Other popular brands D-Link and Netgear generally use 192.168.0.1.