You can create a visual representation of a web page template layout in Photoshop but to make it functional on the web you then need to recreate it in CSS.To use Photoshop to create a sample layout for later conversion to CSS I would look at many different existing page layouts for inspiration and ideas. Pay special attention to the various page widths (in pixels) so when you begin work in Photoshop you can start creating your new document at a good standard width.