I know someone responded to me once before about how to do this. I thought it just involved disabling rich text, but that didn't work on a post that I just tried it on. Also, although I was trying to separate my post into paragraphs, it all ran together in one wall of text. (Strange that this one did not -- is that an effect of the rich text being disabled?)
I am getting very frustrated by everything being so difficult to do and certainly not intuitive in any way!