First thing ....you are looking to edit a map, instead of creating one? and how would this be your world?
Second thing....There are plenty of ways that you can create a world map. How you do that would depend on what programs you have access to. If you are interested in doing that I would suggest reading the sticky found here. It give quite the run down on what is out there. Then look through the Finished Maps forum to see what has been done then look through the Tutorial forum to find plenty of ways to do most of the things you will find in the Finished maps.
Thirdly...what would you be using to edit this map with?
Forthly...If you want a map that is not derivative of someone else's world, I would suggest that you try posting in the Map Request forum (but please read the sticky that you will find there for instructions on how to go about it) or try doing it yourself. We are quite a helpful bunch...if you do not get all demandy on us...and would be happy to guide you on your journey to things mappy
I hope you have fun here