How can I add cod charges. Rs 50 for order less than 500 and Rs. 100 for orders upto 2000 and Rs. 200 for the rest.

StoreHippo allows you to define shipping charges for the orders placed in your store.
You can manage Shipping charges and methods in Settings > Shipping Methods section of StoreHippo Admin Panel.

Please refer the link to add conditions to your shipping status:
http://help.storehippo.com/topic/shipping-methods