Well, you're in the right place! Is your game going to have a static board, or will it be tile-based? Hexes, squares, no divisions? How much territory are you planning for the board to cover: a few miles, a country, a continent?
Do you have any idea what kind of software you're going to be using to create your board? If not, I recommend you take a look through the Featured Maps section and see if there's something there that you like the look of. Usually the author will have mentioned what tools were used, and you can often find tutorials for the more popular styles. This is among the friendliest communities on the Internet, so don't hesitate to ask questions! You're bound to get some high-quality advice.
And, of course, the requisite "Welcome aboard!"