For your lower body I would say just stick with slightly lower weights and higher reps 15-20 range that will keep them leaner, but still retain the muscle. You do not want to lose the muscle you have as that helps you burn fat at rest and keeps your metabolism high

for your upper body if you have access to a gym, maybe start with 2 full upper body sessions and 1 lower a week. For the upper body keep the reps in the 8-12 range to start, you can go heavier later. You can do cardio 2-3 times a week for 30 mins to start and you can increase down the road when you stall.

If you do not have access to a gym the cathe tapes are good, you can either get the slow and heavy series or the muscular endurnace ones. With a minimal investment in some weights and a few tapes you will be off and running. You can get them on cathe.com, or on ebay...but go to her site and you will see what they are about. She is one of the top step teachers in the country and is in fatastic shape becuase she also lifts.