If you select the correct section to add (based on its location), you may add a text widget to that, and apply a background using CSS, letting you do this individually, no matter how many times you wish to use the technique.
Then, in the text widget, you can also apply an image (with a normal HTML image call) which can be positioned over the background.
I'm sorry if this is rather vague, but would ask you to kindly elaborate more about your needs that we may provide a more detailed reply.
Thanks for your patience and understanding!
We look forward to helping you with this.