TOPIC: Creating new icons for Categories

Hi gang
I'm very new to Joomla so feel quite comfortable being in a newbies area
I was trying to create some new icons for the categories but can't get the picture to show.
Even when I copy an existing icon, make a small alteration in Adobe photoshop, re-save as a .png file, upload new image next to the icon part of edit category, choose the saved .png file - it still wont show as a picture.
Is there anywhere I should go for instructions?

What happens exactly? You've selected the image in the category, but on the map there are no icons or what?

Regards,
Daniel

Thanks Daniel
Pictures might be easier

Live page before any changes to the icon

selecting upload new image

image from desktop (same size as sample icons and a 4kb file)

After clicking on save

As displayed on the live page


I've even tried copying one of the sample images to my desktop then using upload new image. It won't display as an image.