Welcome, Mike. "...hope to one day gain enough skill..." ? Well, try a couple of tutorials that seem related, or just that you like the look of, and work through them. Do you already have some kind of graphics software? Plenty to choose from, to suit any budget or inclination. Then pick something modest that interests you in history or politics, and post a work in progress thread, asking for commentary, tips, criticism, reactions, etc.... you'll get a couple to a dozen of all that amazing talent as veritable tutors.

And "...world that currently only exists in my head." ? Great! Now all that's left is to get it down on paper (phosphors, engraved brass, scribed mylar, canvas - whatever floats your boat). <airily waves hand> mere technicalities :-). Seriously - you have a target, and that's a major step toward success.