its ok...! the hindu push-ups really work you over especially your core and spine but as far as your wrists are concerned they play an important role in many sports activities and lifting weights and you really need to strengthen them first. I suggest following exercises.
Wrist circles - Moving your wrists in circular motion from left to right while maintaining your arm in stationary position.
Using Wrist grips - Theee are available in most sports shops should be under Rs. 100 and they give excellent workout. or best is you can use the homemade method of trying to squeeze a tennis or rubber (cricket) ball. it really helps.
These are the 2 most basic workouts you can do. once you practice these for a month or so you can go for a advanced exercise suing weights or resistance belts.
Good luck Aditi.