1. Go to “Appearance >> Widgets”
2. Drag and Drop “News, Related, Slideshow” widget into (any) sidebar
3. In widget’s settings check “Slideshow” checkbox.
3.1 Slider of Featured Images:
It will show a slideshow of recent posts (Featured Images) by default. You can choose category, posts or pages via settings.
3.2. Custom slider:
Check “display custom blocks” setting and press “save” button.
You’ll have 4 new checkboxes: “Display custom title”, “Display custom Image” etc, check it and press “save” button. You’ll have new fields in “Block 1, Block 2, …, Block N”. Choose Images from Media Library.
4. You can set transition/slide time, font/background color, effect, number of slides for a slider.
5. Slider settings can be accessed via Theme Customizer at “Appearance >> Customizer >> Widgets”.