If this is the 4 door Dometic RM1350, the door panel installation is described on page 11 of the manual. If you can't find yours, you can download a copy from the
Tools/Owners Manuals Section of the forum. Also, if you have the RM1350, there is a sliding latch that holds the 4 doors closed while traveling. The latch is slid to the left to open the doors, and should automatically slide to the right after about 5 seconds. If it doesn't, it's probably not wired corrected on the back of the refrigerator. If that's why your food is falling out, you'll need to visit your dealer to have it corrected.
I'm not familiar with other Dometic models - if you have another, you should take a look through your manual - they probably cover these same things in the manuals for other models.