Fernando, the CV shafts are your front axle shafts--they go from the differential (the large central portion of the front axle housing) to the hub assembly holding the front wheels. These are what transfers the power to your wheels, and since they must move up and down and also turn with the steering while doing their job, they have "Constant Velocity" joints at each end (the large portions inside the rubber accordian boots) that can move in all directions while the shaft spins. Since you have an automatic, you most likely have the ADD system--this replaces the need for locking hubs (the rotating dial on the end of most front axles), so you don't need to "lock in" to use 4WD. I must admit, I concur with the other members with their advice to continue your search for a mechanic you can trust, or better yet find a fellow offroader that wrenches on his/her rig and have them over to work with you on some projects. With your extremely limited knowledge (as of this time, anyway), I would discourage you from tearing into anything too difficult--the manuals are usually written for those who have some experience and know what certain parts are called and can fill in the blanks on their own. Don't sweat it--we've all been at the same point as you at one point in time, and had to learn the trade from someone. Best of luck to ya'!
, i hope going to a gravel lot or sand pit confirms the correct operation of the 4WD.
