lol, man well first of all, maybe you should wait on that doobie untill after you are finished learning something new like this
na, anyways you need to paint a map image before you can create one. Dragon needs a bmp image file to generate a new map0.mul file. Unfortunatly right now, the websites here are under some serious deconstruction, and rebuild.. beyond explaination. There were some decent tutorials prior to all of this, but atm its slim pickins untill the sites are rebuilt.
Anyways, scan the tutorial forum here, I think theres something that should get you started in there.
Also, when asking for support, it helps a lot to know what version of dragon you are using... and you can not use Dragon and Map Generator together, as they are completly different programs, even though they both generate custom map files for UO.
in a nutshell, you need a bmp image file, size of 6144x4096 for Dragon, and whatever version of dragon you use, you need to load the color pallete into your paint program to paint the right colors on the image.
Map Generator has a color palette generator built it, that you would run first, and then load its pallete into the paint program to paint with. that should get you started for the moment.