The source folder is just the photoshop sliced images. You do not upload that but instead unzip that to your desktop and use the sliced images to help you re-design elements of the site. Most people do not know nor care with regards to this. You need to know your way around photoshop or similar to use them anyway.
The quickstart is a very different beast. Again, it should not be uploaded viat the joomla back end. The quickstart is a nifty complete Joomla install including all the plugins, modules and components along with the demo data. It is used by those wanting to start a new site with a Joomlart template as it sets up a new Joomla install to look just like the demo.