To add an image to an html input button use this code.

This code allows the button to have an image and text. Note the extra sapce in the Value.

<input type="button" style="background-image:url('icon.gif'); background-repeat: no-repeat " value=" Submit" onClick="docSubmit(true, 'whatever');" />

You may also need to set the background colour to be transparent:

background-color:transparent