Every machine in a network has to have a different IP address or one of them would throw a busy tone back to the router when it called. Addresses are handed out automatically by DHCP at login time but you can allocate specific addresses if you wish, in the Properties page of the network adapter, then TCP/IP and Properties again. Your's would have to be within the range 192.168.1 to 254 with the Default Gateway being 192.168.1.0 or maybe 254. The Subnet will fill itself in. Find the actual Default Gateway by typing
cmd /k ipconfig /all
including the spaces, into the Open box from a Run command.