This tutorial assumes you have some audio files to play with. If you don't, you can usually find some WAV files in C:\WINNT\Media. Note that some features are unavailable for MP3 audio files. WAV files are recommended for this tutorial.
When Mixere starts, it opens a new mix document for you, but the mix doesn't contain any audio yet, so the first thing you want to learn how to do is load audio files. Fortunately, that's very easy. Just select Load Audio from the File menu, or press Ctrl+L. In the open file dialog, navigate to wherever your audio files are, select one or more files, and press enter.
Each track has six buttons (Play, Pause, Stop, Loop, Mute, and Solo) and four sliders (Volume, Pan, Pitch, and Position). The buttons are identified by their icons, and the sliders are identified by the column headings at the top of the document frame.
The track's volume slider is initially all the way left, which means the volume is at zero. Click on the volume slider's "thumb" (the part that moves) and move it to the right. Now press the play button. The position slider's thumb should start moving, and you should hear some audio. If not, see Troubleshooting.