adding image to boxed layout??

I would like to make this site look like the menus with the text boxes in a white background but with the splash of colour image surrounding it. I assumed I could do that in the boxed layout and add an image to the boxed part so that it replicated the menu but can’t seem to find a way to do this? Is it possible using this method or is there a better way to do this??
Logins below

Menu screenshot here: http://www.lilysindianvegetarian.co.uk/wp-content/uploads/2018/12/Screen-Shot-2018-12-17-at-11.27.45.png

thanks in advance