Then you go to the folder and share it so it becomes visible on your little network.
First a small preparation.. doubble click "My Computer" -> go to menu "Tools" -> Folder alternatives (not sure what's the real name in English because my Win XP is in another language, anyway..) -> pop-up window appears, go to "viewing" (again not sure the exact name in Win XP Eng.) -> files and folders ->un-tick "use simplified filesharing.."
Next step..
Right click on the folder you want to share on the network -> properties -> pop-up window appears, go to "share" and tick the radio button -> click OK...