You do if you want to make a map. It takes a long time and you need to be patient with it, but it can be done by a complete beginner. I started mucking around 2 years ago and every day I learn something new. If you have any artistic ability, patience and an understanding of how it works here, you can make a map. My first one took just over a year to make. From beginning to final quenching.
Another way for you to do it would be to post your idea in the ideas forum, and hope someone makes it, or find a map maker and persuade them to make it for you with you doing the xml code for it. That way, you get the medal and experience.
Best advice if you go down the route of you making it is this....
Download GIMP (free of charge software for graphics)
Play with it and learn it over the next few months, till you know what you are doing. So many people post crappy drafts and wonder why it does not go anywhere.
Stay in the foundry, learn the lingo and post your thoughts on maps you see. The more you post in other maps, the more those map makers will help you later.
Then in a few months when you know GIMP, have a good draft post it. Just remember, maps take months, not days.