Roy, absolutely DO NOT tie into the waist belt alone! The harness will come with directions for proper use: be sure to read them, follow them exactly, and practice with the setup before you're up in a tree with it.
I climbed in that harness for years(still have it), as have many thousands of climbers over the years. It's stood the test of time, and extensive testing, research, and field use. It's good, and it works. You must do your part to use it as designed.
For a head start on proper use, see my previous post on this thread.