What you are trying to accomplish is not directly supported by ArduPilot. So it will not likely be easy for a beginner to accomplish.
However, you’ve come to the right place for help! Lots of people on this forum enjoy volunteering their time to help beginners like yourself. So welcome to the community.
Here’s a good “first step” for you: See if you can get FBWA mode working. (I think you won’t need a motor for this.) Here’s a relevant page from the documentation explaining what I mean: http://ardupilot.org/plane/docs/starting-up-and-calibrating-arduplane.html When the aircraft is successfully in FBWA mode, you should see behavior like the video for your ailerons and other control surfaces. (of course you might not have a v-tail setup.)
If you are committed to using ArduPilot for your glider implementation, check out this forum post where someone was asking a similar question: Autonomous Gliding Searching this forum may provide other similar threads.