WP Bakery Visual Composer – wtf?

I have installed Visual Composer – I heard it was the best plugin – you can drag and drop and build the whole site how you want it.

BUT – I seem to only be able to do this in the MAIN BODY of the pages, and not able to alter the ACTUAL LAYOUT of the site, being the header section and the sidebar section.

I don’t need VC for the main body – its just a blog! I NEED it for the ENTIRE PAGE, the ACTUAL LAYOUT.

Wtf is going on here? Is it possible to use it as such and i am missing something?

If you use VC – are you supposed to build the site from scratch IE not use a theme? IS it possible to not use a theme?

I dunno I am stumped… ***How can I use VC to change those other component elements of my site, ie the header and sidebar sections?***

thanks!!