First of all you need to install Joomla theme. It will change the appearance of the website header, footer and non-store pages.
Open template directory and go to the joomla folder. There you can see theme### archive. Upload it to your Joomla admin panel (Extensions > Extensions Manager )
Then install VirtueMart theme. Appearance for the store pages and product listing.
Open template package and go to the sources folder. There you can see theme directory. Open it and upload all folders from there to the Joomla installation root on your hosting server.VirtueMart Guide. Theme installation,