Couple ways to go about it. The best and most suggested way is to do it yourself. Find the appropriate section ie: Town. Regional, Battlemap etc Make a thread stating its a WIP - Work In Progress and use the attachment manager to add your maps to the thread. As long as you don't delete any posts or updates, it keeps track of all revision and is a simple file organizer. Go in the tutorial section find a style or tutorials on how to manipulate the software and make your own style. Try to execute and update as you go along we will try and critique and add suggestions.
On the other hand you can always commission the work. Where the fun in that amiright?