When creating a new template you should first create a new folder inside the "templates" directory.

The majority of the layout is handled through two files and they are layout.tpl.php and style.css so you would take these two files and add them to your new folder.

Now you can upload this folder and these files then change your template in administration -> main settings and you will have a new look to your website.

If you look at your site and see another page you would like to modify but are unsure which template file it is you can add ?debug=TRUE to the querystring and a popup will appear giving you information about the template files in use as well as a list of all the variables available for the page.

Once you get the file name you can then move that file out of the default template folder and move it into your new folder.

68 Classifieds works by using two template paths. The one you have defined and the default. So if it can find a file in your template folder it will use the default.

You can find a great tutorial for creating templates at our user forums.