Hello,
To reduce the space you need to Edit page with WPBakery Page builder >> Edit row settings of the module where you are using slider revolution.
Screenshot for Clarification: https://www.screencast.com/t/ulFdJ2qfU3
To change the background-color of the pages Go to >> Theme Settings >> Styles and colors >> Pages Background.
Screenshot for Clarification https://www.screencast.com/t/lpn5ayEvA
If you are unable to adapt to the changes then provide with admin panel login details and the URL of the website to check it myself and help you out accordingly.
Best Regards.