Rss from html page


i want to create a feed from existing web page for authorised users only.
i know some basics about rss but don’t know how to include dynamic content generated on page to be added in feed.

for example i have small message board and i want to create rss feed from replies to that post, what should i do?

i have created rss feed by creating xml file but that is just static content. do i have to use some php package like simpleXML to create feed xml file on the fly with current data?

i am confused.
please guide me in right direction.

EDIT: reading

I would use PHP to just grab the data you want and echo it out into an xml file.

You could also use an external service like to grab the data for you and format it correctly.