Ok, to set up an RSS feed you have to create an xml file with certain syntax. Below is a sample blank RSS Document.
Code:
<?xml version="1.0"?>
<rss version="2.0">
<channel>
<title>Your RSS Feed</title>
<description>This is what your feed is about</description>
<link>http://www.yoursitehere.com</link>
<item>
<title>This is your first news Item</title>
<description>This is what it's talking about</description>
<link>http://www.linktomoreinformation.com</link>
</item>
</channel>
</rss>
A more specific example can be found
here.
There are additional formats for this also, such as RSS 1.0 and Atom.
For each additional news item you add another<item></item> tag.
You would then save this as something like feed.xml or something like that (the name should reflect what it is about).
Once you create that file, people can "subscribe" to it. If they have an rss news aggregator such as
Sage, for firefox there are also many other readers out there that aren't browser specific, these can be found here:
Feed Aggregators.
One final thing to do is to tie this xml file (your news feed) in with your server side code you are using for your networking site. Use the things people can do in the networking site as triggers for writing a new item to the rss file. You could even make a seperate rss file for each user (depending on how many users you have), and allow users to subscribe to eachothers feeds to stay current on events.
Hope this helps!