Hi Stacy,
each of the sections are given a unique ID named in numerical order so first is #generate-section-1
and to target that section background image would be done like so:
@media (max-width: 320px) {
#generate-section-1.generate-sections-container {
your styles here
}
}
I notice you have text in the image, you may want to try adding the background image without this text. And adding the text in the content, that way it will be mobile responsive. You can do the same (and a lot more) if you use a GP PageHeader which maybe something you wish to check out.