Upload the images you want to appear in the slideshow via File Manager (Tools -> File Manager) to the directory "image_slider". In order for the slideshow to look as good as possible, all images should have the same size (width and height).
Then you go to Slideshow (tools -> Image slider)
There you can add a new so-called slide for each image you have uploaded.
When you feel ready, go to the settings for the slide show (Settings -> Image Slider).
Adjust the slideshow's height and wi...