Hiya! 
The key is to have a background with a window, then “cut out” the window using an image-editing program (I use GIMP, but there are others available).
I can briefly describe how to use GIMP to cut out a window, if you don’t have another preferred program and haven’t done it before.
Alternatively, you could ask for help from some of these fine people in the art resources topic. 
For example, here's one I cut out for my story:
This is what I had before:
And I made it into an overlay, like this:
The overlay you make should be the size of the entire zone (640 x 1136). It should be at a layer where people inside the house are behind it, and people outside the house are in front of it (ie. the overlay is at layer 1, the people inside are at layer 0, and the people outside are at layer 2).