OK, let's start with the basics ... besides getting an account here.

Record show: Mac - I recommend using GarageBand, but you can use the free Audacity.
PC - many here use Audacity, it's a free download and offers many features.
You'll want a microphone, if not provided with your computer. Any USB model costing at least $15 will give reasonable results but you'll want to spend at least $50 if the sound of your own voice is really important to you. If you are just stringing together MP3s, you don't NEED a microphone.
Turn OFF your system's speakers!
Record (and edit(?)) your content.
With your content available, plug it in to your editor - Audacity or GarageBand - and listen to the result. Make sure your levels are loud enough to be heard but not popping into the red (cut-off) zone. Export the result when you are satisfied. If you are using GarageBand, this is where you would have added in your Cover Art.
Now open up a browser (Safari, Firefox or (shudder) IE) and go to your My Podcast page. Click on "Post new Episode" (I think) and fill in all the boxes supplied. ALL the boxes. In ORDER. Not that they all matter, this just helps keep the confusion to a minimum.
Post it!
The blue line should move across your screen until done, and you've uploaded your first episode. You might - MIGHT - want to start with something shorter than you expect will be typical. This way things can go wrong much more quickly and you can get a good result that much faster.

Questions?

Dave M