I'm trying to do the same thing and can't get it to work either.  I've tried putting the image in the images folder and referencing it both ways:  ../images (like the rest of hte images in the minimal extropy menu.css file shows) and straight images.  The images, as background, will not appear.  Is there some other CSS setting that is needed?   I am using the DNN Navigation Provider, not Solpart.

OK, bear with me here.

I'm trying to use a background image in a css class that is used in the DNN menu (DNNMenuNavigationProvider)..

I'm using the Minimal Extropy skin which has a menu css file in a folder below the skin.

Here's what I've tried:

1)  put image in the same folder as the menu.css class.

    CSS:

     .homeSelected
{
 height: auto;
 width: auto;
 border: thick solid #00CC33;
 background-image: url(nav_Community_active.gif);
}
 

I know it's picking up the class because the ugly border I put shows up.  But it doesn't show the image.
The css class is the last in the menu.css file. 

2) I tried putting the images in the same folder as the skin and referenced it in the menu.css class as follows:

background-image: url(../images/nav_Community_on.gif);

The image still does not appear.

3) I changed the image ref in 2 above to:

background-image: url(<%=SkinPath%>/images/nav_Community_on.gif);

And still no luck. 

How do I get the image to appear?

Thanks.