To achieve a text and button image overlay, set your image as the section, row or column background. If you'll be using a row, adjust the Row's Top and/or Bottom Padding to display more parts of the image.
You can also opt to use a Gap element instead of padding. The Gap element has the advantage of being a responsive spacer. That means you can hide or show the gap depending on screen size using the Hide During Breakpoints feature.
Hope that helps.