Icon size for home page

So I have modded some modules and have the info displaying properly (I will fix the security tomorrow, thanks Alex!).

My question now is, where do the icons go?  I have them in /media/images/mobile_icons

but they display blank on the phone.

Is there a size limit?  I have them in PNG format.

Thanks!

Enter full path to the image, for example:

{site_url}modules/boonex/news/templates/base/images/icons/mobile_icon.png

{site_url} is automatically replaced with your site base url.

Once again, thanks for your help!