the big first question is : do you have the TW cat extractor?
if yes, then its a matter of playing with it. you wont remember which file is in which folder. but you can browse each folder and you'll start to get a feel for whats in each. the first one is generic game object inis, second one off limits (the actual lod models) and from there its typically grouped by decals, aircraft and ground models, going down the line of sf2, vietnam, europe, israel, north atlantic and DLC (if you have any)
it seems daunting at first. play with it, practice, screw up, learn from screw up and practice some more. eventually you'll start having the game dialled in the way you want rather than adjusting to the game