Slideshows are a collection of signboards that rotate through on your display. In order to create a slideshow, you need to have at least two signboards created. A tutorial on creating a signboard can be found here.
To create a slideshow, tap on the Slideshow icon on the bottom navigation bar. If this is your first time, tap on the Add button in the middle of your screen. Otherwise, tap on the Add Slideshow button.
You'll see a list of signboards you created. To add a signboard to your slideshow, simply tap on that signboard. You should see a border around the signboard to indicate it has been selected. To deselect, simply tap on it again.
Tap on as many unique signboards that you want included in the slideshow. To change the time interval of transitions, tap on the clock icon and choose the interval you like:
Name your slideshow and tap the check mark to save your slideshow. The save slideshow will appear on the Slideshows page.