Big help :rolleye2: Why bother posting ?
2WD is normal (rear wheel drive)
4WD Hi is for slippery/wet/snowy/etc. conditions where additional traction is wanted (front and rear wheel drive). Usually can be used up to 40 MPH or so. Can usually be shift-on-fly at low speeds.
4WD Low uses the transfer cases Low range, when additional torque is needed (you're really stuck, steep hill, heavy load, etc.)
Should only be used under poor traction conditions, a low speeds (you really can't go fast in low range anyway), and not on a dry pavement. Come to a complete stop before shifting in/out of Low range (not shift on fly).
You don't have any manual hubs to get out and lock/unlock.
There's more to it, this is just the basics.