I don't know that you will find a lot of tutorials about DNG specifically. Once you have converted a raw file to the DNG (Digital negative) format, it is no different working with that file in Camera Raw or Lightroom than it is the original raw file. However, I checked on Adobe.tv and there are a couple of tutorials that might help you. Here is the link:
Just a word of caution. I looked at a little bit of the first tutorial, and you have to go through about nine minutes of clowning around before they get to the discussion about DNG. You can drag the slider past all of the stuff you don't want to watch.