Any map you make can be given to your group whether its flat or a heightmap. A heightmap is a map that isnt flat land. It has hills, rivers, ponds and all sorts.
To make a heightmap you need to have a program that would let you switch between Greyscale and RGB mode. If your unsure you can try downloading GIMP, its free and you can switch between the two modes.
But before i tell you about that do you know what some of the options do in Map Maker? Have you used Map Maker before without trouble?