Hook the wire clips onto the pads (closed loop at the bottom), then press the pads at the bottom with your fingers once in place. The spring fits against the caliper bracket as you do this - it mustn't be trapped between the pad and the bracket. Pressing both pads in at the bottom as you do this allows you enough clearance to slide in the metal wedge at the top which should be greased and held in place with its own small spring clip.
John
December 2007