How to create a slider & add images in WordPress

The instructions state: You haven't create any slider yet. Go to the media library, edit your images and add them to your sliders.
How is this done?

Steps: 

1. Go to the media library
2. Edit the images you want to be in a slider (best size 1170x500)
3. At the bottom of the window, select "Yes" to add to a slider
4. Create the slider if you haven't yet got one (give it a name in the box and select "Add a slider")
5. Add your title and description text for the image (these will show up on top of the image in the slider)
6. Select update
7. Go back to Customiz'It! to tell the theme to use the new slider you have created