"Add to cart" and "Quantity" buttons

hey if any one can help me to add “add to cart” beside “Quantity” buttons display under each product in all shop pages inculuding of course categorie pages i mean the client have not to go inside prodocut in “single prodcut page” and make their choose , i want you can add to cart and indicate quantity if you want . plzz i find this option in other themes , but not in Mystile theme i want someone can show me a code or something i can add to plzz