Bill is correct. The most time consuming and most detailed is finding and/or making a good dds, or bmp. I am trying to find a good picture of a military ambulance WW II, a direct front-end shot. Everyone posts pictures at an angle, which makes it difficult to get a good bmp from.
Good searching is a must, and good techniues in Paint Shop Pro or Adobe or the like is a must. (which I'm not so hot at either!

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After finding a good picture make it a bmp or dds, open up a program called dxtbmp, and save as dxt1, 3, or 5. 5 is the least compressed (bigger) but better quality. Put this texture into a folder where you can easily access it. Call it up to apply all or various parts of it to your object in FSDS, OR go to poly mode, click on poly, then texture, then custom circle, then texture properties. Drag the lines with handles (sometimes kind of hard to grab the handles (go to 200% makes it a bit easier to see them), and the handles around the part of the texture you want to use. Might have to fuss with it to the texture doesn't look wiggley.
There's a lot more... a lot more! Let me know if you wish further help. Bill L and n4gx are some of the many giants on whose shoulders we stand!

Extremely knowledgeable, very helpful.
BTW- You're design looks great. I might suggest using more sections for your tires... 15 or 16 so they look rounder. True this increases the poly count, but You are building a good looking missle launcher, not building for a 386 computer with 512k memory! Hahaha!

Bob