having a nightmare connecting to the net via ethernet on 2nd hand powermac g4

hi! please help!

i am having an absolute nightmare trying to connect to the internet via ethernet on my second hand g4! i have everything required;

ip address
subnet mask
default gateway
dhcp server
dns servers
physical address
(all these i got of my old pc which is currently still set up to the internet vis wireless)
i am linking up straight through the ethernet , bypassing the linksys WRT54GS ver.6 router

it seems i have all required numbers, as above, but when i go to set up the connection, it asks for the router address(which I gather is the physical address?). whenever i try to set up the connection it will not let me input the router adress as it has letters in it!

what do i need to do????

this is really baking my head!

arrrgg!!!!!!

anyhelp much appreciated.

thanks

izzy