Most of the work of creating slideshows in Lightroom is done in the Slideshow module, where you can select layout templates, choose transitions, and set playback options.
In the Slideshow module, the left panels contain a list of templates and previews of their layouts. The Slide Editor view in the center of the workspace displays the photos in the selected slide template. The toolbar below the Slide Editor contains controls for playing a preview of the slideshow, refining the selection, and adding text to the slides. The right panels contain controls for modifying the template, adding text to the slide layout, and selecting playback settings. See Slideshow module panels and tools.