An RSS feed is a way for you to see new information that comes out for a sitekeep up to date with changes on a website. In the case of the LMF these the changes are new files available to shared with a group. You would can subscribe to a feed, which is similar to bookmarking it, and every time you looked look at your subscription you would see the latest news for that feed.
Both Internet Explorer 7 supports and Firefox support RSS feeds, and so does Firefox.
Podcasts are an extension of RSS feeds, where you can see the latest music and video files are the focus instead from a website of news. You would subscribe to a podcast just as you would in the same way that you subscribe to an RSS feed. If you use a media player that supports podcasts, such as iTunes, it will automatically download the music and media files for you.
Note that you can You can mix music and video files in a an RSS feed with normal files ( like documents ) but anything anyone subscribing to it as a podcast may only see the music and video files.
You will now see on the information screen for a group, the feed icon and the words "RSS/Podcast feed" and that's your feed!