Apart from the question whether it is allowed to do this (copyright and Mudcatiquette), you have to give the size in pixels (or alternatively in percent of the window size, but this tends to distort images). Or you do not give the size, then the image is displayed in its original size (which is in your case a good approx to your requirement).
To place it in the center (what you tried to do with align="middle"), you have to put it in a center tag (align does not work for images - heaven knows why).
So to do what you wanted, the code is: <center><img SRC="http://www.jazclass.aust.com/bt111.gif" ALT="Music Notes and Rests" ></center>

MudGuard