Hi Collette,
If you are looking to add a copyright for your site's content, you can look into adding a Copyscape banner to your site. A
Copyscape banner will warn potential plagiarists against taking your content.
Now in terms of your podcast, you can get a
Creative Commons license for that, it is free and I have done so for both of my podcasts. Once you go through the licensing process (you can do it right on their website), you can post the Creative Commons emblem on your site alerting visitors what they can and cannot do with your podcast. You can see an example of where I posted my banner on Your Blooming:
http://www.yourblooming.com/ (down at the bottom, it is the emblem with the CC on it).
I hope that helps!