Color Section element

Hi
I inserted a color section on my Custom Order page (at the bottom) for now. I use: alternate content, with image, fixed, center center, stretch to fit, no min. height use content within section to define section height, large padding, no border styling. I would expect my section image to fit within the content area and not overlap/conflict with my sidebar.
Do I misunderstand how this element is meant to work?
Would appreciate clarification and help in having the background image appear only in he content area leaving the sidebar as is.
Thanks
Lyse