Upon arriving, there will be a marine on your right; kill him to get a shotgun. If that is all you have it won't last long as two Demons, a man, and one or more flaming skulls will also be in the neighborhood, and their welcome is not very friendly.
Once you kill off this welcoming committee, go forward. There are two ways to go forward around the column. On the right is a 10% health pak before the step, on the left is a 1% health vial before the step. Both lead to a platform, and to your right is green armor. Forward and to the right of that are more shotgun shells and to the left is a 25% health pak. You will probably encounter another flaming skull.
You can also reach the above area along the left wall at the first break to the right. You may also meet two demons (one invisible) and a man.
If you continue along the left wall at the second break to the right is a small room containing a Cacodemon, some health and a box of shotgun shells. If you need them, have him chase you, then double back around the other side, but you may want to be careful that he doesn't trap you in there.
** To Be Continued **