Most of the Joomla sites use single template for all the pages. But Joomla supports more than ONE Template in a site. The following steps help you to use more than one template in a joomla site.
First of all, you need to install all the templates that you want to use (Extensions --> Install/Uninstall and upload the template package). After installation, you can assign them to the pages/menus/components where you want to use the different templates.
You Can assign Different templates to Different Menu items. Click on Extensions--> Template Manager. Now Select the Template which you want to assign to a particular page (menu item). Once you have Selected the template, e.g. FSUG, on the left side of your screen you can l find a Menu Assignment window.Here, click on Select from List, and then choose the menus / pages where you want the template to use and click Apply or Save. This can be done for each template that you want to assign to the different pages. Make a New Look and feel for your web site and Enjoy.