Jomres template files can be found in a number of different places due to template override and template package features, so how do you find which template you need to edit to change the layout?
In Site Configuration, go to the Debugging tab. At the bottom there is an option called Dump Template Vars. When this option is set to Yes, the frontend templates will have their output modified to look something like this. As you can see from the image, the full path to the template file and the template file name itself is displayed. Additionally, if you hover over the path with the mouse then the names of the variables that can be used in that template are shown.