To use option 7, you will have to add the components to the multiplier board, including the two ribbon cable connectors. You will then need to make up the mating cables and solder the wires to points on the main circuit board. There may also be some trace cuts on the main circuit board. The DC508 manual should have a section on option 7 and how it interconnects with the main board. Getting the manual for the DC508 is the first step...
