At the most basic level, you can use Windows Recorder to record audio files for your students.  But there isn't much versatility, nor editing features, which you will eventually want.
 
I got most of my information from the below sites at the initial stages.  The tutorials are fairly easy, assuming you have the time and the patience to make a few mistakes.  Exactly as the site recommends, I downloaded Audacity to record all my audio.  If I speak too softly, am not clear, get a frog in my throat--whatever--I just re-read the section, and then later edit out the problem.  I can change volume and speed, too.  Although the whole process becomes pretty simple once you get the hang of it, expect to spend a solid afternoon tinkering with the software.  When recording your files, you will want to consider clarity as well as file size. 
General info: 
http://www.podcastingnews.com/articl...o-Podcast.html http://radio.about.com/od/podcastin1/a/aa030805a.htm 
Audacity: 
http://audacity.sourceforge.net/ 
Good luck. 
Chris Cotter 
www.headsupenglish.com