Thumbnail on main page

[jcaparco]

This may be a stupid question, but I can not figure it out!
On the main page, I have my categories. How can I get the categories on the main page to show a thumbnail? it just list the categories, and the number of ads, but no images. Once you click into the category there are images, but I want this on the main page.

I have seen sites that show a picture next to the category, but I can not get that to work.
One site is the demo here, Viper Alley. They seem to be able to get the image from the latest ad to show up in the category. That is what I am trying to do,

The URL is http://usedtoolshed.com

I am only testing right now, the site is not live

[Chuck S]

You can as admin view an ad and mark an ad within that category to be the category avatar using that link MAKE INDEX THUMB