OK, take a look at this example menu
www.idea-box.co.uk/modx/. I assume this is what your trying to achieve. You can get more information on Wayfinder parameters here
www.muddydogpaws.com/development/wayfinder/parameters.html, it explains them better than I could.
First of all, I created two images for each of my top-level menu items, one for the normal state and one for the expanded state. Then I created two template variables to hold each of the image states. One called [*menuImage*] for the normal state image and the other called [*menuImageActive*] for the active or expanded state. For both TVs, I used the following settings - ’Input Type: Image’ and ’Widget: Image’. I then applied each TV to the template my top-level pages use.
The next step was to add my Wayfinder call to my template:
[[Wayfinder? &startId=`0` &hideSubMenus=`true` &parentRowTpl=`parentImgTpl` &parentRowHereTpl=`parentImgActiveTpl` &activeParentRowTpl=`parentImgActiveTpl`]]
I use three custom template chunk parameters here because Wayfinder doesn’t use images as menu items by default and I need to include the TVs created earlier.
I created a chunk called {{parentImgTpl}} and added the following code:
<li[+wf.classes+]><a href="[+wf.link+]" title="[+wf.title+]">[+menuImage+]</a>
[+wf.wrapper+]
</li>
This chunk is used by a document that is also a container but IS NOT in an active/expanded state. In which case, we include a placeholder [+menuImage+] for the [*menuImage*] TV that holds the normal state image.
Next, I created a chunk called {{parentImgActiveTpl}} and added the following code:
<li[+wf.classes+]><a href="[+wf.link+]" title="[+wf.title+]">[+menuImageActive+]</a>
[+wf.wrapper+]
</li>
This chunk is used by a document that is also a container and IS currently selected. In which case, we include a placeholder [+menuImageActive+] for the [*menuImageActive*] TV that holds the active state image.
The final chunk parameter &activeParentRowTpl also uses the {{parentImgActiveTpl}} chunk. This displays the active/expanded state image for the parent menu link when one of the sub-level documents is selected.
Does this make it any clearer? I should point out that I’ve only tested this with two levels of navigation. I don’t know how it would look with more levels. Also, because I’ve used the &parentRowTpl parameter in the Wayfinder call, the normal state image will only be applied to top-level documents that have children. If you have any documents without children (the About Us link in your original post?) they won’t have images applied. You’ll have to use some of the other template chunks, perhaps &rowTpl and &innerRowTpl?