There's lots of ways to find interesting sources to add to your Digg Reader.
Browse in Digg Reader: We've created a Browse section in Digg Reader, filled with interesting blogs, magazines, and news publishers that are recommended by Digg's editorial team. Just click on Add, then Browse Categories. Then explore. When you find something you want to add, just click on the "Add" button. If you've already added a source, it'll be marked with a check.
Search for Sources You Already Like: You can also click Add, then type the name of a source you'd like to add. Hit return, and you'll get a set of search results, which will (hopefully) include the one you seek.
Add an RSS Feed: When you find a site, blog, or other source you'd like to add to your Digg Reader, just look around for its RSS feed. Copy the feed URL, then return Digg Reader, click the Add button, and paste the URL into the box. Hit return, and your source will be added.
Most sites with an RSS feed put a link to it on their homepage. Look for the universal icon for RSS feeds: