The simplified instructions to install the tray are as follows:
1. Unbolt the box from your truck. On a Ram the bolts are removed from the bottom and on a Ford and Toyota the bolts are removed from the top.
2. Remove the tailgate. 
3. Disconnect the light fittings, bumper and gas cap
4. Use a crane or ask 4 friends to help you lift it off.
5.  Use an overhead gantry crane or forklift  OR 6 Guys to help you lift the ute tray onto the mounts.
6. Bolt the frame mounts to the frame of the truck.
7. Lift the UTE tray onto the mounts
8. Bolt the tray to the mounts
9. Connect the light fittings and parking sensors
 
Installation is not difficult but you will need a forklift / gantry crane OR the help of 4-6 friends.