The Magento frontend is not a single file. It is a combination of blocks nested in each other. Each block is an object you can play with.
Open a category page in your shop and you see a lot of frames which all represent a block. Some blocks are structural (left column, right column, content, and footer) and others contain content (product list, cart, navigation, and so on).
In the next two steps, we will enable the frontend hints to get an idea of the used blocks on a page.
Enable your frontend Template Path Hints. Go to System | Configuration | Developer and enable the template and block names.
Reload the frontend. When the frontend hints are enabled, a frontend page will have red frames around each block.
Each block with a template is in a red frame. The title in white is the template file and the blue title is the classname of the block object.
When you want to edit the content of a block, you will have to look at the files...