to add an RSS channel go to any website with RSS find the site with the RSS, click on the XML, RSS, Podcast ICON (there may be other types of icons that work too and so does some html links), a message will appear asking you if you want to add the channel, select YES and viola.
All podcasts at
Magnatune are good for music. this is one where you must click on a url. Once you go to the site on your psp's web browser select the genre of music you like, click on "subscribe", the message asking you if you want to add the channel will pop up, select yes, and you've got it.
i think the thing to know is that you do not want text based rss.
ironically, if you open the "non text-based" rss not on your psp, a page filled with the RSS's script will open. Stupid Psp brouser.