How to extract subtitles from MKV files

Hi, I was trying to extract the subtitle file from a certain video in MKV format. But I couldn’t really do it. I used MKVToolnix, but I could not find MKVExtract anywhere in it. What I want to do is to save the subtitle file elsewhere in my computer, and not to make changes to the original video. How can I do this? Any help is greatly appreciated.

http://www.videohelp.com/tools/MKVExtractGUI

Thanks. I got exactly what I wanted.