Once you login to the website, go to Smart Slider > Dashboard on the left navigation bar.
Select Edit on Homepage Slider
Duplicate one of the slides by clicking the three dots ( … ) .
Open the new duplicated slide. It should look like this:
Click the + in Thumbnail in Content and upload a new image or select from the Media Library. Also, if desired, change the link to the website page, the slide title and description.
Click Style and click the + to upload the new image.
To Unpublish: click the three dots ( … ) then click Unpublish.