Hi,
You need to add a little more info, however check the following. You say the starter motor is ok, so I assume the engine turns over. If the engine turns over, you need to check that you have a spark at the spark plug when the engine spins. If you have a spark, then check that fuel is getting to the engine, take out a plug and it should be very wet with fuel after you've spun the engine over. That should give you a start point for diagnosis.
Cheers now
Ken Chapman, August 2007