Overlay text and button on slide show

I would like to overlay my slide show with some text and a “find out more” button. How do I do that?

Add your button in the same container the slideshow is placed into.
Change button position to absolute. Then with CSS (top/left/bottom/right properties) adjust the position of the button like:

#mybtn {
   bottom: 20px;
   left: 20px;