Rose,
This is going to be really hard to do just like the ToolTips in Swing with only AWT...
Personally, what I would do is make a TextArea that only displays help text down in the corner of my app somewhere, and then use a MouseMotionListener to detect what component I am over and send strings to the TextArea...
You could try and make ToolTips like the Swing ToolTips by using a MouseMotionListener, detecting what component you are over, and painting a rectangle and strings over the components on the screen. However, this is going to be much more difficult... you are going to have to ( at least ) mess with fonts, and possibly have to make special components so that you can paint over them... It's possible to do ( especially since the programmers at Sun did it in Swing ), it's just a bit more in depth...
HTH,
-Nate