Right, heres the basic wiring diagram. Im not a professional by the way, as you will probably tell!
Each oem boot light needs 2 bulbs. Each bulb has a positive and a negative, therefore you have 4 wires that need turning into 2 wires for ease.
Now imagine your boot is open above you. I put one bulb on either side of the oem light. One far bulb and one closer bulb. To connect the 2 wires of negative, think of the main wire going to the closer bulb with another single wire between main wire and the bulb like so:
To ground these lights iv used a handy little ground point on the boot lid itself, if you take all the plastics off, on the drivers side of the boot lid you will see a ground point. I just crimped a circular connector onto the end. Does that make sense so far?!