If you are planning to do another Joomla install in the home directory then you can move the current J/VM site into a new subdirectory by simply dragging & dropping all files & directories into the new subdirectory using Filezilla.
OTOH if you want to keep that Joomla installation and just add another template then install that new template, make a new home page menu item in Joomla & assign your new template to that new menu item.