Theme PHP Code for "Add order to cart" etc

Hi there,

Im currently working on a shop for a computer store, I want to style the products list like this:

This is what ive made so far as a actually theme:

Link to my php file:

What i need to get on with this is pretty much to figure out how to add the "Add to cart" link to my image before getting any further.

If there is a list somewhere with all the tags i can use i would be very greatfull for a link.