The easiest thing to do is to listen to the Podcast and record it in real-time by hitting Record in Audacity to record "What You Hear".
If you're having trouble check out the Audacity Team's "FAQ: How to record the speaker output".
(Short-form blurb, see full text at link for full info):
One of our most common questions is "How do I record sound from
YouTube or other streaming videos?" or "How can I copy audio from
files that Audacity doesn't recognize?" The answer to both questions
is to record the speaker output as the sound is playing.
Unfortunately, this is not always as trivial as it first appears to
So, putting aside any conspiracy theories or cries of incompetence,
there are three different ways to record this kind of audio...
- Select it as an input in Audacity and click 'Record.'
- Plug in a "loop-back" cable.
- Obtain new hardware or software.
Another utility specifically meant for recording 'everything' is Total Recorder:
An ideal tool for recording streaming audio, Mic input, or Line-in
input from external devices connected to your PC. Video Pro Edition
also allows you record video from screen or a video device like web
cam or TV tuner. Convenient and powerful scheduler allows you to
record when you can't be at your computer. The functionality of
background recording makes the process of recording streaming audio
and video handy and efficient!
If you want to just 'rip it', without listening, that will be more difficult and will depend on the source, the type of podcast, etc.