You can use either the white wire or the purple/green pair of wires to trigger for testing. Apply power to the box and place the coil wire close to a ground (frame, motor, etc) and tap the white wire to ground... every tap should give you a spark. For the purple/green pair, use a jumper (I use a paperclip) to short the two together. You should get a spark when the jumper is open.

As Denny said above... go to MSD website and you'll find the instruction sheet