How to edit the front page of my dashboard?

I want an area on my dashboard where the users on my site can post problems. I have registered a shoutmix box but I have run into one problem: I can’t find where to put the shoutmix on my page! I have put it at the very bottom, but nobody sees it. I want to put it just above the “Dashboard” header on the main dashboard. I don’t know which PHP file I should edit to place it in! Anybody help me??