Try these fitness classes: Basic Step, Water Aerobics, Abs classes, Jazzercise, or Yoga for Beginners. Spinning or indoor cycling classes also make great options because each student can control their workout speed and resistance levels. You'll probably get a lot out of a few personal training sessions, whether you need general instruction, help designing your own program, or fresh ideas. See if you gym offers general "Instructional" classes that are catered to both beginners and individuals who want to increase their fitness knowledge. Look for an introduction to free weights or a beginner's guide to strength training, taught by a certified trainer or instructor.
Workout videos to try: The Biggest Loser – The Workout, Cathe Friedrich's Low Impact Step, Bellydance Fitness for Beginners, Safe and Fit at 50, Leslie Sansone's Walk Away the Pounds, Denise Austin's Burn Fat Fast