Bud,
I have layed down carpet in a number of cars and trucks over the years. Its not a tough job. Mainly, pull up the old stuff, clean out all of the nasty debris that end up below it. You might want to remove the sound deadner as well, I normally do. You can buy this stuff by the roll or cut to fit (it should be silver on one or both sides, I like the silver on both). Here is what I normally do;
Start out by laying your new carpet out in the garage for half a day. This will help smooth it out some, as it may have folds from shipping.
1. Clean the bare floor pan surface. This is also a good time to spray down an undercoating type material. You can ge this from just about any automotive store. I like using it becuase it will stick to anything and creates a better sound and heat barrier than paint.
2. When this is dry lay out your sound deadner/heat shield to fit the area. Note - it doesnt have to cover every square inch, just the main areas.
3. Get some of the spray adheasive and spray it down on the surface. Then apply the sound deadner and stick it down good.
4. Use the old carpet as a pattern to lay out where to cut needed holds for seat bolts, light switches, etc... Use tape on these areas and then lay the carpet in place to make sure that the areas are correct.
5. Cut you holes only big enough for the needed area. Most people over cut carpet.
6. I dont normally spray adheasive between the carpet and deadner. If you need to pull it up for any reason, it will shread the deadner material.
7. Just lay the carpet down, smooth it out, let it sit for a while, then bolt everything back in place.
Hope this helps. Good luck with your project.