If you already have some favorite blogs bookmarked, select the bookmark and go to the site. On your URL bar you should see an orange symbol with white lines. That is the standard symbol for RSS feeds. If there isn’t one by your URL bar, you can look around the site. On many blogs there is a feed button on the front page.
If you don’t have any favorite blogs yet, you can use Google Blog Search to find one you like. If you like books, for example, type the word books into the search field. The results will be blog posts containing the word books. Read some of them and pick one you like. Look for the orange RSS feed symbol and click it. Follow the instructions after that to add it to Google Reader.