This exercise is a squat; when first starting into a weight workout, you should always learn the squat movement first. What I have Erica do is really imagine she is sitting into a chair. When you sit down into a chair, the first movement is the hips moving back, the knees slightly moving forward. The weight is going to be in the heels and the shoulders are slightly coming forward. When you are first doing this exercise, keep the hands out in front to keep your balance; so slowly moving down to where you feel comfortable but on further than 90 degrees and then come back up.
The speed of this exercise should be no more than 2 seconds on the way down and 2 seconds on the way up. This exercise targets many muscles; the glutes, the quads, the hamstrings and the calves. Exhale on the way up and inhale on the way down. Do this exercise about 10 to 15 times. You can do 2 to 3 sets of this exercise, then move on to the next exercise.