if he has connection with his broad band router, he already has a network setup. all he needs to do is set up file and print sharing (i.e. right click your hard drive letter, go to sharing and security or properties and go from there. if you haven't activated sharing already do that.) if you want advance sharing you will need to go into folder options (you can do this a couple of ways, but just go into control panel and click on that, scroll all the way down, and click off simple file sharing).
i'd do a search on the web and find setting up home network, file sharing etc.
just make sure that you have security features set up for you folders or you have enabled security features on your wireless router, otherwise anyone who can hop onto your wireless network can get to your files