This screencast should get you going. Click 
for full screen.
PI Maps is a tool for storing and sharing spatial data. It is currently in a public beta testing period, so the functionality may change from time to time. PI Maps uses the Google Maps API to allow viewing and input of points, lines, and polygons. PI Maps runs on Google App Engine, so it takes advantage of Google's robust storage and server infrastructure, which allows users to have confidence in their data's well-being. To top it off, the part of PI Maps that runs in your browser was built with Google Web Toolkit.