Navigate to System > Configuration
On the left sidebar, beneath "infortis extensions" click "slideshow"
Find "main slideshow on home page"
This list will reflect the CMS blocks that comprise the home page slider. They will be in the same order as listed below.
To edit any of the slides, simply find the CMS black that contains that slide. In the example above, the slides used are "block_slide1", "block_slide2" etc. (this is the block ID - not the block name)
To create a new slide, make a new CMS block under CMS > Static Blocks. Then, copy the Block's ID into the list as seen in the screenshot above.