Hello,
First you need to create a slide. As soon as the slider has been created and configured, new slides can be created and assigned to the slider.
In the edit slide page, there is the option to assign the slide to a certain slider, set the order, and other additional slide settings.
Please follow the complete guide about sliders.
https://xtemos.com/docs-topic/how-to-add-slides-to-the-slider/
If you have any questions feel free to contact us.
Best Regards.