where do i put php-code for a slider?

Somewhere I got to put this code echo do_shortcode("[metaslider id=340]"); in order to place a slider on the homepage. The homepage is a site that shows the newest content and not a particular fixed site. I´ve already tried to put the code into the home.php file, but I can't manage to position the Slider on top of the Site, but below the menu. Now the slider is at the bottom of the website. The domain of the Site I´m struggling with is: http://www.ghsreutlinger-koeln.de Thanks a lot for any kind of help!