Have you had a chance to use the 4WD yet?
So when the lever is down you are in 2 hi or rear wheel drive.
To engage 4 hi (4WD) I'm generally moving slowly straight forward, place the transmission into Neutral, then pull up on lever, and then move transmission back to the D or drive position.
Part time light should be on.
To disengage 4WD Trans back into neutral, push down on lever, trans back into drive, Part time light should be off.
Keep in mind that command trac is for slippery surfaces only and not for bare pavement, otherwise binding will occur. You don't want to damage the transfer case.
4 low (I call it slow) I have used off road especially on steep downward hills, which is very good, crawl speed, trans even in 1st gear.