First of all, welcome and congratulation for having your nab up and running! You passed the most difficult part already!
As far as the RSS feeds are concerned, you are almost there!
Let's yahoo as an exemple, since you find some overthere.
This address got a nice list of RSS shortcuts, that are ready to use:
Just right-click on the orange icone 'RSS', copy shorcut, and paste into the address entry. Name it whatever you like, and you are good to go!
I love the RSS feed, it works really well. But you have to select them carefully, otherwise your rabbit will spend most of its time reading internet link. Just try them and keep the one you like!