Torque is a game engine, not a 3d modelling program.
Filetypes and how to make them:
.cs - Script - Edited and made with notepad or any other simple text editing program.
.txt - Text - As above
.gui - Gui - With editor enabled, press f10 to open the Gui Editor, or use a text editing program.
.mis - Mission - With editor enabled, host a non dedicated server, and press f11 to open the Mission Editor, or use a text editing program.
.ter - Terrain - With editor enabled, host a non dedicated server, and press f11 to open the Mission Editor. In the menu, find the terrain editor.
.wav - Sounds - Not sure what to use for editing sounds, however there are plenty of resources on the Internet. Can be converted to and from other filetypes, however it is recommended that you keep them short in length, as they can take up a lot of space.
.ogg - Music - Best way is to edit them with a program to keep them short, and can be converted to and from other audio filetypes. They aren't as big as .wav files, however the quality may not be as good.
.dts - Shape - Created and exported from programs such as Milkshape, Shaper, and Blender.
.dsq - Animation - Not sure on how to do this.
.dif - Interior - Not sure how you would make this. I've never done this. However there is a Map to Dif conversion program somewhere.
Image Files - Made with your favorite image editing program, and many resources on the Internet. For shapes, I suggest you use the images already provided, or an image that is all 1 color. A logo or something may be okay.
.dso - Compiled - An unreadable format, these are used for the default game scripts.