There are two things at work here. 1) The transmission - Drive, 2, and 1 are just as they are for an other car with an automatic transmission. I assume you have been driving long enough that you know a bit about that part of it so I'll skip it for now. 2) The transfer case - This is where you will find 2 High, 4 High, and 4 Low. 2 High means that you are in Two wheel drive and all of the engine's power is going to the rear wheels. This is good for gas mileage. It also reduces wear and tear on certain parts of the drivetrain. If the weather is good, you will usually want to keep it in 2 High whenever possible. However, in the snow it is quite different from a front wheel drive car. If you don't know the differences between FWD and RWD you could end up spinning if you get too lively with the gas pedal. 4 means that you are in four wheel drive. This is NOT to be confused with All-wheel Drive! If you haven't ever driven a 4WD in slippery conditions it might take a little getting used to. I can't think of how to really describe the feeling to you other than 'unique'. It's more like RWD, but kind of like FWD becuase it's both but neither... just go into an empty, snowy parking lot and have fun ;) In general, 4 High is where you want to be for bad weather; mud, snow, ice, etcetera. Your handling will be different and your gas mileage will take a small hit, but you'll be slightly safer in the bad stuff. Bear in mind that 4WD does NOT make you invincible though. 4 Low is not useful for most people. I live a mile away from pavement, but my road is PACKED dirt so even I wouldn't need it unless we got a foot of snow. (About 5 times a year.) 4 Low is like 4 High but there is extra gear reduction in there that makes everything seem like it's about a gear lower; Drive is about like 2nd, 2nd is like low,and low is... LOW! Your top speed is reduced enough that you can forget about highway travel or fuel economy but you can pull things really well, climb hills great, or get yourself out of deep mud or snow. Unless you are pulling trees out of the ground, stuck up to your axles in something, or trying to climb a steep hill, don't bother with 4 Low.

I have an Envoy with nearly the same thing. "Four High" should be used for driving in snow. "Four Low" is strictly for extreme situations, such as getting stuck, really stuck in the snow. I have never used 4 Low. In 4 High all four wheels are moving so that is what gets you out of the snow, and or deep deep mud. I have a button that switches from two to four wheel,its a snap. There are times I shift down to "3" to slow the engine down.

Make sure you're sitting down... I'm not sure if you want help only with the 4 and 2, or with the drive, etc as well. So therefore, I'll start with the P-R-N-D-2-1 lever. This controls your transmission. Each letter represents a gear: P - Park (Wheels will not move, used when vehicle is parked) R - Reverse (Vehicle will drive backwards. On a steep hill it may roll forwards but this is not good for it.) N - Neutral (The wheels are free. They can spin at any speed in any direction unless the brakes are applied. In this gear, using the gas pedal will only rev the engine, and not drive the vehicle.) D - Drive (Most common gear for automatic transmission drivers. Allows the vehicle to shift through all gears (from 1 to 3 in your case) The vehicle chooses the best gear, starting in 1st gear and changing accordingly with the speed) 2 - 2nd gear (This is similar to Drive, except the vehicle will not shift to 3rd gear. It will stay in two only. This is used sometimes for climbing hilly roads, as it keeps power going to the wheels. It is also useful for starting in slippery conditions.) 1 - 1st gear (This does not allow the vehicle to shift out of 1st gear. It is used for off-roading and low-speed applications.) A few notes on the above: 1. To shift out of Park on most vehicles, you must apply the brake pedal or press a button on the gear selector (that stick that is pointing out of the floor). 2. When going down hills, etc. the 2 and 1 selections may be used to 'gear down'. This means that instead of using the brakes, the engine can slow down the vehicle or help maintain a speed when going down a hill. This saves the brakes but uses a bit more gas. 3. The vehicle can be shifted between D, 2 and 1 while moving, but don't shift from D to 2 or 1 at too high of a speed. Now, for the 4H, 4L, N and 2H (Transfer case gears) 4H - Four-wheel drive, high range This means that all four wheels are driving the vehicle (normally two wheels drive and the other two just move along). The high range means that this can be used for high-speed (upwards of 70km/h) driving, although that isn't recommended usually. This is usually used for light off-roading on dirt roads, snow, ice, mud, etc. It should never be used on dry roads, as this is bad for the entire system. Before using this, be sure that there is always something other than road under your tires (like driving on a layer of snow). 4L - Four-wheel drive, low range This means that all four wheels are being driven, like 4H. The difference here is the 'low range' part. This means that the vehicle should not be driven at high speeds (keep it under 30km/h). To keep it simple, the vehicle gears down extremely low, so when you use 4L the engine will rev up faster than normal. This is fine, do not worry. 4L is for serious off-roading or when trying to crawl out of somewhere after the vehicle is stuck, trying to tow something, etc. *To shift into or out of 4L, you must put the transmission in Neutral, set the emergency brake, and completely stop the vehicle. N - Neutral I know what you're thinking "He's just repeating himself". No. This neutral and the neutral on the transmission do the same thing but are seperate. This is used for towing. If you ever get your vehicle towed, you need to put the transfer case into neutral. If you don't, then the wheels will not move freely. Unless the tow truck driver puts the wheels on dolly's (hard to explain) then this must be done. 2H - Two-wheel drive, high range. Your vehicle should be in this mode most of the time. It means that only two wheels (the back wheels in your case) are driving the vehicle. This can be used on all surfaces, at all speeds, in any conditions. However, if you find that the wheels spin (while driving on ice, for example) you can choose to put the transfer case in 4H for added traction. I am tired right now so I hope I didn't miss anything or confuse you. Please let me know if you would like more explanation on a particular part. Good Luck, Hope this helps