Okay, simply put, you use layers in photoshop itself.
You create a new layer (shift+ctrl+n) and place a piece of map on that,
press ctrl+t and change the size to your liking, and position and rotation
then go edit>transform>perspective to make it look like its tilted sideways like that.
To create the edges, hold ctrl then click on the layer of the cut out pieces of map in the layer window on the right.
that selects the outline of the layer, then do edit>stroke