Editing existing content

I did a search but no luck. I creatd a page, then today went ot edit it after a friend told me its not validating. I noticed that the page does not have a “P” tag in the content, but has the “closing P tang” after each paragraph. I removed it all, then deleted the page, then proceeded to recreate it. But the same things happens. the opening gets stripped out when I apply a “div” to the headings.

I did not see a way to edit my page in HTML, and not sure how I can correct this. Any Idea as to why this may be happening?