Trouble getting started..Need some help for an absolute beginner

I bought TGE about a week ago, and it wasn't what I thought it was, but that's no problem. I thought I was buying a library for C, my mistake, it does state this after closely looking. Anyway, the problem I have is where do I start. All I've been doing for a week is modding the FPS starter. I am very impressed with the on-the-fly ease of use in TGE, so I'm disappointed in purchasing TGE, it's well worth $100.

First: I would like to start with the Tutorial base, and start scripting, as well as calling C++ functions. Can someone point to which file to start with if I run the tutorial base. Maybe from there I can start following a little of the process, until I get "3D Game Programming All-In-One", should be here this week.

Second thing: I went through the tutorial directories and it might help if I new what these files are for:

.cs
.cs.dso
.gui
.gui.dso
.ter
.mis
.dif
.map
.dts
.dsq
.ml
.dml

Any help to get a more descriptive understanding of those file extensions would help too ( And not just telling me that .ter is for terrain and .mis for mission)

Thanks, from a struggling newbie scripter.