Firstly with XP Home you are limited to 5 concurent connections so if you have more than 5 computers you are going to have some problems.
But having said that you should start off with running the Network Setup Wizard on the XP unit and enable File & Printer Sharing and when you get to the end og the Wizard make a Floppy Disc that will allow you to install the XP networking protocols onto the other Computers.
Once you have the floppy made insert it into one of the computers make sure that everything is connected and then run the floppy. You may be asked to reboot the computer and if that happens remove the floppy before performing the reboot and then reboot and follow the prompts allowing File & Printer Sharing.
When you have done this an all the computers you then need to share something so that the files or printer can be seen and used by the other computers to do this right click on whatever it is that you weant to share and on the drop down menu chose Sharing and left click on it. Different OS have different directions here but it's a follow your nose type thing and you shouldn't have any problems.
When it comes to the Printer open the Printers on the machine that it is installed on and again right click on the printer and chose Share, you'll need to give the printer a name but generally the default will surfice. Just a note of caution here as you haven't stated the Make or Model of the printer it's possible that it may not be possible to Network it and if that is the case you'll need to install it on the newest computer and then transfer the files to that that you want to print.
Col