popcop - my 2 cents: there are tons of good free news scripts at hotscripts, sourceforge and freshmeat. Find one that is close to want you want, figure out how it works and customize it. That will be an easier and quicker way of learning for you than trying to write one from scratch with limited knowledge.
Once you have the one you pick functional, and you understand the concepts behind it, then you can try writing one.
That is how I have learned php.