Wenham breaks this chapter down in a simple way, and I give it here: Moses’ command to Aaron and the congregation (9:1-4); the congregation obeys (9:5-6); Moses’ command to Aaron (9:7); Aaron obeys (9:8-21); and fires comes down from the Lord (9:22-24).
Application: With much detail and with much ceremony Aaron and his sons engage in the proper worship of God. We have already said words along this line, but they continually bear repeating. It most definitely is the case that so many people have more regard for their own wants than they have anything with respect to the Lord way and will. Looking at 8:36, can we interpret (and act) in any other way? While Aaron had two sons who did not pay as much attention as they should have, let us not be guilty of the same.