comment notification

I own a social networking site and users are complaining that when they get a comment, it doesn't show up on their home page. Other things (like a new message, group invitation work fine. So all I need is, a notification on their home page, that shows they have <#> new comments, and when they click it, they get taken to their comment page. The site uses Smarty. This isn't a terribly hard job, I've used PHP before, but Smarty confuses me slightly. I don't have a HUGE budget being a student. Any sympathy gladly appreciated! xD