If you are looking to specifically tone up and strengthen your lower body, then you should look at weight training for your lower body.
There are several exercises you can perform, with the use of free weights, and machines that will help you in your weight training goals.
The squat is a very effective exercise, and in fact made it on the list of the five exercises you should do, because it works many muscle groups at one time, meaning you can make the most of your time.
To do this exercise, with a weight positioned behind your back, and feet shoulder width apart, lower yourself into a sitting position and back up.
The lunge is also a very effective exercise that made it on the list of the five exercises you should do, for the same reason as the squat. It works many muscle groups at one time, which allows you to make the most of the time you spend on your workouts.
To do this exercise you will want to stand with feet hip-width apart, toes facing straight ahead or angled slightly outward. In this position, you will then slowly bend your knees and lower hips towards the floor, keeping your torso straight and abs tight.
Keep your knees behind your toes; make sure everything is pointing in the same direction. Never lower yourself more than 90 degrees.
Do this exercise three times a week on non-consecutive days, and do 2-3 sets of 10-16 reps. You can do this with or without weights.
3. Calf Raise
This exercise can be done with or without a machine. You should stand with the ball of your foot elevated (with the use of a stair, step, or chair).
Keeping your body straight, press with the ball of the foot and lift your heels as high as possible, and hold for four seconds.
Then, keep the body straight while lowering the heels keeping the ball of the foot on the ground. Repeat these actions without letting the body sway back and forth.
All of these exercises done together and in a routine will help you in weight training for your lower body. As with any weight training routine, you should practice the necessary form to avoid injury, and never try to do to too much too fast.
Good luck to you, and may you reach your fitness goals with ease and efficiency.