To build strong, muscular calves, try the 'step up' exercise. Stand on a step or stairway on the balls of your feet, leaving the rest of your foot off.
Use a wall to balance yourself so you don't fall. Rise onto your toes slowly as high as you can and hold for the count of three. Lower your heels below the step.
Using your calf muscles, push up onto your toes again and lower. Repeat 10 to 12 times. Add another set as you get stronger.