How do I load/use a custom map?

[dandavis]

Sorry for the relatively dumb question, but I'd really like to tweak and then use one of the maps that came with the game. Specifically:

1) I want to limit the number of starting provinces available to increase my chances of beginning in a comfortable location (I prefer playing from corners, as we all do, right?).

2) I want to limit the number of neighbors that provinces have - mostly to limit the AI's tendency to "jump" oceans and invade some of my coastal provinces. (Note that I am not referring to the seafaring races here, but the land-based ones). I want to be able to establish choke-points on the map - provinces that you can fortify with the expectation that a land-based AI can only approach you from that direction.

On the Urgaia map in particular, I don't consider this cheating. You all probably know the province that should be a proper choke-point - the long, horizontal province that connects the larger Western continent to the Eastern continent. I don't feel that a land-based AI should be able to avoid that province and cross the middle sea to invade my coastal provinces. Rather, I'd like to grab the entire Eastern continent and relax behind a nice fortified city... but thusfar, I've been unable to achieve that on the map editor.

Anyway, I'm not totally unfamiliar with the map editor -- I've certainly played around with it -- but so far, I've found it clumsy and I don't know when I'm playing on my tweaked map or not. if someone could give me some very basic but detailed instructions on how to adjust a map in the manner that I've suggested, I'd really appreciate it.

Thanks.