Hi Saaby,
Can you describe what steps have you tried so far?
In general, for basic home networking (i.e. workgroups, not domains) it should go like this.
After two computers are hooked up to a router (they don't neccessarily need to be running XP, but say they are in this case), and turned on of course /ubbthreads/images/graemlins/wink.gif, either one should be showing both computer names when you go to Start/ My Network Places/ Entire Network. You may have to drill down through Microsoft Windows Network/ Workgroup, etc.
To keep things short (it's easy to find step by step instructions all over the web... start by going to microsoft.com), choose which folders on which drives you want to share on one or both machines. To do this, right click on any drive or folder and choose Sharing. You can set permissions and security on items or just leave everything wide open. If you have good protection from the outside, leaving permissions wide open is convenient, but is still one less layer of security.
For those who want to share printers over a home lan, the basics are:
First turn on printer sharing for the computer that is physically hooked up to the printer. Then go to a different computer, go to Start/ Printers and Faxes. Double click on Add Printer, go through each question the wizard asks and away you go. It should be able to detect the printer that is now hopefully showing on the network, and the printer driver will install itself from off the other machine.
Like mentioned, you can find all the detailed step by step info, but there's the basic concepts to help get things started in the right direction. This also works over wireless.