I want to have it so that as you take damage/lose health for your vision go black and white showing you getting close to death

You need to select the “set members” node and in the details panel that shows up on the left, pull that out so you can see everything in there and check the box that says “scene saturation” I think it is, and pretty close to the top. Then once you have that it should show you 4 floats all 0. That should be all you need.