Deleting background image

I have added a background image using simple full screen background image, but it has only put the image on the right hand pane, I would like it on all the screen.
I have tried removing it but cant see how to do it.

I am struggling with this, and I thought I was IT literate.

Are there any simple basic guides to taking me through the logic of setting up a static home page, with no sidebar, just menus to take me to other pages, and how to set these menus up to go to the actual pages, I am becoming balder as each day goes by, I am sure one day it will just click – I Hope