Add an Ajax history function to a Wordpress theme

I use the Vinz Wordpress theme. This theme allows to navigate without reloading the page: [login to view URL] A click on a project leads us to the project page while the post is loaded via Ajax. I would need a click on the logo to leads us back to the homepage without reloading the page. Actually, the function exists. If you go on a project page, you will see a square at the left side of the page. I would need the same behaviour set on the logo.