Thank you for the links to the information.
Normally with a Garmin autopilot you have a VNAV button. I just wanted to confirm that this will work with the touch screen 750/650.
For non Garmin autopilot aircraft one has to essentially manually adjust the verticle speed using VNAV but with Garmin autopilots you hit the VNAV button and set your altitude to the loiwest point and your good to go.
Thanks again for your replies.