first of all you need to make sure your dimmer can operate 450 watts (some can't, 50 x 9 =450)
after you have made the apropriate holes for your lights you should start at one end and "loop" from each light to the next, then take your existing light fitting apart and note which wire goes where (very important)
the single cable you have should be connected via a junction box to where the origonal light was connected (probably two blacks which will be your neutral, and one single black which will be your switched live)
switch on and enjoy.
When i say "loop" i mean that each of your new lights has a pair of either terminals or wires, you should connect the black wire to the fitting which is marked N or is blue, and the red wire to the terminal marked L or is brown.
By starting at one end (this will only have one red and one black) you then do the same to each light except that you will have 2 reds and two blacks, (one from the previous light and one for the next light)
The bare copper wire you will also have is the earth wire this should be covered in green /yellow sleaving and connected to the erath terminal of each light (they will probably have one since they are mains)
you should end up with just one cable which you connect to where your existing light was, since the first light where you started is now the end, and has no other lights to "loop" to, so it only has one pair of wires un like the rest which have 2
