For Add slide in Homepage / Front-page slider, please follow below given steps :
1. Click on add New slide option under Featured slider in admin panel[1], after click you will get a form for add new slide.
2. In Open Form Please Enter slider title [2], Slider Description [3] , Featured Image [4].
3. After set / Fill details please click on Publish [5] for get your slide live on your website.
**If you want to add and save only your slide(s), not want to publish , then please use save option, don't use publish option.