Hi wpurdom!
I would recomment that you check the stikied threads in the modding forum and the wiki. Download the official DB from the
Official Files for Modding thread see how things are done there. If you have specific questions please ask.

Basically all information is stored in spreadsheet files which can be read using the free
Open Office,
MS Office Excel or a similar program. Events and scenarios are written in a script language in these files, other things like unit models are a "simple" list (the columns of the spreadsheed have often notes attached, very useful to check these, especially for the unit and model files.). The data from the spreadsheet files is converted via a tool, the
CVS-Splitter in a format the game can understand. You wil find a short guide how to convert the files also in the thread mentioned above.
Good luck.

Cheers
Norbert