Dumbbell exercises are a great way to incorporate muscle stability. Machines control the movement or range of motion and are perfect for beginners. 
Dumbbells, on the other hand, are more advanced and without proper form and technique could lead to injury. I have put together a few exercises that can be performed by using dumbbells. Please modify each exercise if you are unable to perform the ones shown, or if they cause pain. The key to the perfect workout is modifying lifts or exercises to fit your body. I recommend doing three sets of twenty repetitions for those that are wanting to tone and four sets of ten repetitions for those wanting to add muscle mass.
Top 10 Dumbbell Exercises