Making changes to Highend for WordPress

Hi,
First off, I have the main demo for the theme Highend for WordPress installed in WordPress, which came with Visual Composer, and I am attempting to proceed with swapping out things on the demo home page with my own content. I have been able to make a few changes to things like color and some of the text. But I have no clue how to swap out pictures that came with the demo– either that or delete them (and other elements) and just add new ones in Visual Composer that I can toy with. Is there a good tutorial that covers rebuilding a home page from a Highend demo template? Thanks.