How were you able to check the battery to determine it was good? Many times batteries can have power, but not enough to start the vehicle. This usually means that they either need to be charged, or replaced.
If the vehicle is turning over but not starting, then there could be multiple things to check. You need air, spark and gas for an engine to run. If any of these are problematic, the vehicle may not start.
It's also possible that there is a problem with your starter. Without seeing the vehicle these are just a few ideas. Good luck.
〉 Answered on Oct 28th, 2008 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines