how to display custom icon in welcome screen

I want to add custom item in welcome screen. For this I added custom item under /apps/wcm/core/content of mixin type cq:console. Now I could see my custom item.  I tried to add the value of the property called "iconClass" as "customitem" and uploaded one image named customicon.ico under /apps/wcm/core/content just same as other items(siteadmin, tagadmin). But I could not see the custom icon. Could you please let me know what needs to be done?