Lay the cushion in front of the rail around 4 inches away. Start on one end and place the cushion on the rail. It is best to do this with 2 hands. One hand holds the cushion away from the rail the other pushes the cushion onto the rail. Be careful and make sure that the top of the cushion is flush with the top of the rail.
Contact cement is dangerous stuff.
If you screw up it usually will not let you go back and fix it. Once again take your time and don't rush things. Once you get all the cushions in place walk around the table and pull vertically on the cushions walking you hands down the rails. This will make sure that all of the cushion is contacting the rail. You do not want voids in between them as you will end up with a dead spot in the rail.