Cut a piece of 2x4 to be about 10" long. You are going to screw this to the 18" long support that you previously screwed onto the body. This is what is going to hold the head/back rest at a 25 degree angle. Before you attach the support, place it on the first support and lean your head rest against it to decide where you need to attack it to get the headrest to fit on at a 25 degree angle. Once you found where you are going to attack it, screw it onto the bottom support.