Hmm well you should have 4 wires coming into a little box in the right side of your boot.
2 of the wires are for one speaker and 2 are for the other.
You need to find out which 2 wires are wired in to the right speakers and which are wired into the left. Do this simply by using your headunit and telling it to put all the sound to the right.
Once you figure out which wires do what you should label them somehow, black tape on one set and red on another would be fine .
Then run a 2 core wire for each speaker from the speaker to the right side of your parcel shelf.
Now you need to connect the right speakers to the right hand one and the left to the left. (obviously lol)
If you are using the block like I said from halfords you need to attach the little crimps to each wire then fit them into the box accordingly.
I think that covers everything!