If you want to add a favicon to your AxShare site, you'll need to use the Plugins feature. But first! You'll need to host your favicon on a hosting site. If you haven't found one yet, I just tested this with IconJ and it gave good results.
Once that's done, the hosting site will give you the favicon external link code to put into the <head> of your site. Copy and paste that code into the AxShare plugin area, like this:
The last step is selecting which pages you want the favicon to show up in, and you should be good to go!