How Do I Insert an Image Slider Into the Header?

I am using X with the Icon stack. I have found the PHP script for the header, but I do not know where to enter the tag

<?php layerslider(6) ?> in order to have a slider play in the header instead of a static logo. Can anyone advise on this?

(the tag was generated by the “Layer Slider WP” plugin" if that makes any difference)

Also, I want to make the background in the header black, it is currently white, where do I do that?