How to change drupal commerce views like checkout,payment? i configured drupal commerce module all working fine.question is how to format or design the checkout page,billing page,review page,payment page. i can add more data but how change existing data..i make tpl file for related name but by this we can add more data but how to change existing data plz tell me ASAP.

in detail:actually drupal commerce provides four page for checkout (1)checkout(2)billing address(3)order review(4)payment all are working fine problem is: can i change the all four page's design and add more data to it.how can i find out the html of these four page. i can't figure out by making template file of those four page.
Have you learned Views?
you can try change default views shoppingcart,checkout page,billing page,review page etc.
Eg: to modify shopping cart block you can go to
http://your.site/admin/structure/views/view/commerce_cart_block/edit