Maps for Undead Hunt are created using TilEd, a super-awesome free map editor (it’s amazing, really).
Here’s the link to a handy guide on how to do it:
Map Creation Guide (pdf)
Here’s the package countaining what you need to create maps!
..and play them
Access the option menu form the Undead Hunt main menu (you should have already placed the map on your device memory card, before this). Then tap on the “Load user generated map” button, and navigate the file browser to select the map file.
Map files are represented by this icon: