Thank you so much for using our theme.
First Go to Setting > Reading > Static Front Page and choose a page for your front page.
And go to Appearance > Customize > Featured Section Options then Enable Feature Section
Please have a look on our documentation too. https://doc.acmethemes.com/supermag/#Howtosetupfeaturessections
Similar type of discussion is also here: http://www.acmethemes.com/supports/topic/featured-slider-category-slider/