understanding php…

So I am trying to add links to my “friends” page and when I click on “add links” in the content area of the page it doesnt appear. Now if I was dealing with html and css I would know how to fix this but because there is no html page (that I know of) I am trying to understand how php fits in as a substitute for html. Can anyone give some insight about this or point somewhere I can gain knowledge on the subject?