You can find your own messages and posts by going to your profile page. That's the little person-shaped icon at the top of the blue area on the left.
Edited to add: To find podcasts, click on the "Ideas" link on the left. After you've done that, you'll see a link for "Podcasts" in that same blue area. If you click on that, it will bring up a list of the podcasts.
Hope this helps!