It should be pretty simple for your pop up since there really isn't much plumbing. It depends on how extensively it was done, but it really just involves flushing the rv antifreeze out of the water lines. You can do this by filling your fresh water tank and running the water through the lines until they are clear. If antifreeze was put into your freshwater tank, you are going to want to fill and drain this a couple of times before running the water through the lines. If you have a hot water tank, hopefully there was a bypass installed and the tank was bypassed when it was winterized. The bypass will be a couple of valves with a tube between the inlet and outlets of the hot water tank. Be sure you turn off the bypass so that water can enter the hot water tank when you are ready to use it. Always drain the hot water tank after every camping trip to prevent bacteria from building up in the stagnant water. The only other thing I do after I flush the lines is pressurize the system and check for leaks, and then I go through the camper to be sure all the systems work (refrigerator, hot water tank, stove, ac, furnace,etc.) Check your lp connections and lines with soapy water to check for gas leaks. Also check to be sure exhaust outlets are clear of any nests from wasps, mice etc., like the outlet for the furnace. I sometimes run some cheap vodka through the water lines to get rid of any residual rv antifreeze taste, but the rv antifreeze won't hurt you and the taste should go away on your first camping trip.
