Right, you will need approx 25 new plastic clips. These consist of 2 peices, part that attatchs to the car body work and part that clips to the actual bump strip. Its VERY easy to swap the clips, the parts on the strips slide in place and the bits on the car twist out/in.
When you buy them make sure 1) they give you enough, 2) they give you the red ones that go on the ends to make the fit tighter.
Worth wile mod the phase 2 ones look so much better, I managed to get mine second hand and they happened to be colour coded to my car!
Think I paid about £30 for them.
Worth wile looking out for the lights and boot strip as well by the way.