The first step is to get your home wireless network configured properly. Bradley Mitchell, the About.com Guide to Computer Networking, has a fantastic and easy-to-follow primer on networking that's a great place to start.
Microsoft also offers a handy tutorial on wireless-networking basics that will help if you're using Windows. If you're using Vista and running into problems, troubleshooting guide will help.
If you're using Windows 7 and want to share a printer on a home network, follow the links at How to Share a Printer on a Home Network with Windows 7.
Next, learn more about the basics of wireless printing with a primer from Etan Horowitz of the Orlando Sentinel.
If you're trying to use a scanner that doesn't have a network card, you can find some useful software from Remote Scan.