If you want to shift the background on one of your Divi Theme sections, you can do with Divi's position settings.

For example, suppose you have a section with a background, and some content (an accordion in this case), like so:

Note that a negative vertical offset moves the section up, while a positive offset moves it down. Similarly, a negative "horizontal offset" moves it left, and a positive one moves it right.

Of course, this shifts all the content of the section too. To make sure only the background is shifted, we can simply shift any rows in the section by the same amount in the opposite direction. In this case we apply a positive offset:

For example, if your section is in a standard post, you could crop any part of the background exceeding the boundaries of the post content area with: