This is going to be a links post rather than a detailed explanation. The reason being is that there are a lot of good explanations already out there. There are a lot of programs on the internet you can create rpg maps with, I'm just going to talk the ones I've used. Lets start with the easiest Pyromancers http://pyromancers.com/dungeon-painter-online/ This is a flashed based website embedded tool that allows you to draw grid based dungeon maps. Its wiziwig, just click on the style of tile you want, select rectange, eclipse, custom polygon etc and draw some shapes. Its a very quick and easy way of producing room/dungeon layouts. The end result isn't very graphically distinct and creating unconventional shapes can be a bit of a pain but it works. You can export your creations as image files. I used Pyromancers quite a bit at first, as it was a very easy way to create excessively large dungeon maps. http://www.hexographer.com/ Hexographer comes with a free ware...
Histories & Fantasies