First, you must add new page, give it name and choose the "home slider" in Page Attributes option at right side of edit page.
In Home Slider Template you will not find options like other template. You must create your gallery first with "Add Media" at the bottom of text editor.
Upload your image in that gallery.
After that, see at the right side of that option and find gallery settings. In Gallery Settings you can add Title for the Heading at front of background. Caption for the text under title and Alt Text for URL Discover Button.
That settings made for one image, so you must add your setting PER IMAGE. If you have 4 image you should make 4 setting too.