Hey Supriya,
Stair climbing should be avoided by peoples having any knee, ankle, hip problems. While doing stair climbing as a workout you need to keep a good posture. Keep your back straight and look forward. Dont lean forward. Wear a proper shoes to support your foot arch. Also, Stair climbing would help more to loose body fat percentage rather than toning your leg muscles. So you can do some weight training exercises if you really want to get a better toned leg muscles.