<a href="javascript
:void(0)" onclick="javascript
:document.body.style.background Image='url(
http://www.imagenestop.com/items/car...527.jpg)'; document.body.style.backgroundColor='none';"><img style="width: 40px; height: 40px;" src="http://www.imagenestop.com/items/carros-para-descargar-26538.jpg" /></a>
aqui vez una modificacion
del codigo velo