Reworking some new landclass areas.. best way to begin?

Hello everyone, I've been reading through some of the posts here, trying to decide on the best way to proceed with a project I want to work on. The scenery around my local area (Corpus Christi, Texas) needs a serious facelift, especially around the airport. If I wanted to rework the default landclasses around the city and airport, what would be the best way to begin learning this project?I already have the terrain SDK, Ground2k4, USAPhotomaps, the ECW stuff, and various other utilites and graphics editors.I'm having a hard time trying to figure out just where the Corpus terrain files are and how to locate them. I'm sure I need some lat/long coordinates first, but not sure of the best way to find these and the files.Any help or links would be greatly appreciated. Phil