The best way to proceed is make sure you have a good graphic editing program. Paint might not be good enough.
Think of it this way. You have three colors to play with. You have Black, White, and something else (doesn't matter what it really is, blue, red,etc)
Anything in Black will be black in the maze template you create with that image. Anything white will be erased (white) in the maze template. Anything in between will become the actually maze template. You should look at the masks in the Gallery:
http://mazecreator.com/maze_creator_gallery.phpThe best example is probably the Elaphant (sorry about the spelling):
http://www.mazecreator.com/gal/Elaphant.bmpTry applying this mask to a large BOX style maze. You can then try to apply it to different shape and size mazes.
To generate that with a picture will take some finesse. Depending upon you picture editor you us, sorry, sellout should be Silhouette in the manual, gutta love auto spell correct with Word. If you can get the outlines of your picture (if your tool allows layers you can freehand the tracing), then you can fill sections with your desired color.
The best thing to try for a dog would be to erase (paint white) all around the outside of the dog shape. You might want to add black highlights in some areas of the dog such as the eyes, feet, maybe in patch on the coat if that is what the dog looks like. Save it as a BMP and try loading it as a MASK. Start with a very large maze (to get as much detail as possible) to see what Maze Creator did with your image.
Depending on how close it was, you can touch up with the build in maze tools or you can go back to the painting program and edit your mask.
Hope that gets you closer, feel free to followup with more questions. Let me know what photo-editing tools you have, I can help a bit with Photoshop and a few others.
Regards,
Greg Peatfield
Maze Creator Author