Help with columns and modules

I want to add a strip of color behind a picture kinda like the one on the picture here… 1 but i want it to be longer… as it is now, it’s an uploaded photo set as the background of the column… but the problem is that i can’t scale it properly if i want it longer, which I do and doesn’t seem efficient. is there an easier way of accomplishing this?

thank you!

Can you share your page URL? may be :before or :after CSS sudo class can hlp you

I haven’t published what I’m working on. I’m working on a template.