How to add icon to one menu item?
To add icon to one menu item you should to add attribute icon into one item XML tag. Also you should adding two attributes for the icon width and height. If you use more than one icon with same values of width and height, you can insert attributes iconWidth and iconHeight only once, for the first icon in Menu Structure.
<item title="Desktop" icon="Desktop.gif" iconWidth="16" iconHeight="16" />
<item title="My Documents" icon="MyDocuments.gif" />