I'll use some of my maps as examples:
A small map, your first map doesn't have to be real world nor does it have to be hugehttp://warlight.net/Map?ID=11383
When i started making maps this was my first one.
After you get used to it, then move on to more advanced maps like this:http://warlight.net/Map?ID=11654
Then you can go crazy on your maps and start creating ones like this(Note: this map is still in development):http://warlight.net/SinglePlayer?PreviewMap=30518