Don't know of any sites, but I learned by trial, error and forum posting :-)
The easiest way would be to use a combined wireless router and modem with wireless recievers on each PC.
I did it the hard way - I share a freeserve ADSL connection using an ethernet modem, wireless router and wireless recievers. This is what I did:
First connect the ethernet modem to directly to your PC to set up the connection to the ISP. Then unplug the modem from the PC and put it to the router. Finally set up the router. I have to do it this way as my router doesn't enable a PPoA connection (which we use in the UK), so I have to set up a dynamic connection, using my host name as the server (for freeserve, user.fsnet.co.uk), and then enter the MAC address of the modem. Took me days to figure that out!! But as I say, get a wireless router/modem and you'll be laughing!!!