Change the homepage hero image
The Onyx template has a different homepage banner, here are the steps to edit this image.
Go to the WordPress dashboard > Pages > All Pages
Select Edit on the Frontpage
Click on the image – this will open up a panel on the right-hand side. If this doesn’t appear click on the gear icon this will open up the settings area
Click on the Background Settings arrow – this will open up more details
Click on Edit Image and select your photo if it has been previously uploaded or upload into the media library.