Don't worry, you are almost there! Just download and install "Gantry Framework for Joomla..." (first Link) from here:
After installation, re-visit your website and you should see the site with the right template styles and fully functional. You can at any time restore your previous template in your Joomla! administration.
This template is based on the Gantry Framework from RocketTheme, LLC and brings a bunch of hot features to your template that otherwise wouldn't be possible in that quality. Thank you for your understanding.