Help with my Logitechs headset (earphones and microphones)

Hi, I have looked for help and tried almost everything I can think of, and
now I hope you are able to give me a few more ideas. I have a Logitech
Headset, I was able to get sound through the earphones no problem, but unable
to get the microphone to work.
Microsoft help has told me to go to my Speech Recognition tab, click Audio
Input, and then click Properties. However I do not have a Audio Input, only a
Auido Output, and there is only one tab choice unlike what help says.
Microsoft help also suggested to check that my mic wasn't muted and my volume
was up. I checked in sounds and audio devices and all my volumes seem to be
at a good volume with nothing muted. The only last suggestion that I am able
to find is to check to see if my mic is on and plugged in properly. I have
done all of these things a few times over and was sure to re-test my mic, and
still nothing is coming through in the test hardware area of my sounds and
audio devices.
Could it be my sound card? How can I tell if my computer had the capability
for a microphone?
Thanks for any suggestions you may have.
Monique