Install new Wordpress Theme to new website and migrate content from old Joomla website

I need help to Install a Wordpress Theme I purchased for a church website to a new test site on our host and assist in migrating relevant content from an existing Joomla website to this new WP site. The after that, give a quick training on how to update content in Wordpress.

WP theme demo link: http://nazareth.axiomthemes.com/home-3/