Use all the submenus media images and add them to the background carousel of the homepage

Site URL: https://www.faunesque.com/

Hello there !

I have finished my website using the Forte template : www.faunesque.com
As you can see, on the homepage background, I have 6 images playing (one for each category of the "Artwork" menu). I would like to add more images without adding any new categories. Is there a way to use the categories of the "Sketch" menu to add some images in the background carousel of the homepage? I already asked the chat and they told me that it might be possible with the css custom. I ain't no developer, just want to know if it possible for now. 
Thanks a lot for your help :)