Hey Kittie,
While you can plug a mic into the pod it's probably not going to give the best sound (unless you're going for a special vocal effect). You can also plug the mic directly into the mic input on your soundcard, but again this won't give the highest quality sound either (probably worse than using the POD).
For better quality a dedicated mic preamp is the best way to go. I know it's an extra cost, but what kind of budget did you have in mind for your mic and were you looking at any specific mics?
For more details I have a lesson about connecting various types equipement up to a soundcard located
here.
Here the section that deals with connecting microphones.
Hope that helps.
-tkr