You don't remove the assembly.  Inside the hood, in front of the radiator
are the headlight assembly dust covers.  On the passenger's side, you may
need to unbolt the coolant recovery bottle for best access; on the other,
there should be JUST enough room in front of the battery to get your hand
back in there.

Make sure you open the OUTWARD cover (turning clockwise and not very far),
as the inner ones are for the "brights."  Take off the cover and put it off
to the side, then pull off the electrical plug connector off the bulb.

The rest of the directions are in your owner's manual.  You will need an H7
bulb - in a Sedona, I recommend an upgrade to a Philips NightVision or maybe
a Sylvania SilverStar (though the latter doesn't last very long).  Make sure
you NEVER touch the glass on the bulb with bare fingers - only the base.  If
you do, clean the glass with a clean cloth.

To summarize - the HARDEST part of the job is that metal retaining clip that
feels a little like a paper clip.  Getting it off is easy, as you just push
in on the spring (towards the front of the vehicle) and then you should be
able to lift it up and turn it out of the way.  You then just pull the bulb
out.

But getting that clip back on, while at the same time making sure the bulb
is in the EXACT correct position can be a real job, especially if it is cold
outside.  The key to the bulb positioning is to note the notch in the bulb.
In Sedona's I believe it should go straight up, though in some models, it is
straight down.  But it will be one or the other, and it only fits in
straight and completely one way.

Once the bulb is where it should be, theoretically you should be able to
just turn the metal connector in, again push in on it, and slide it down
into position.  Sometimes you can (and should be able) to do it in seconds.
There are times it has flummoxed me for 30 minutes, but that is my level of
incompetency.  But then put back on the electrical connector, and it should
be fine.

Before you put the cover back on, you may wish to start the van, and make
sure the new light works.  Looking into the headlamp lens, the bulb should
be in perfectly straight, and not tilted up or down.  If it is tilted, you
installed it incorrectly, though it is very hard to get the metal spring
retainer on it if it is installed incorrectly.  Re-check the direction of
tha notch on the bulb.

One more note.  If you are going to upgrade to a better bulb, best off
replacing both at the same time.  Once you have successfully changed one
bulb, the other should be easy, as you are now an expert.

Sorry for the length, but hope this helps.