Yup, pigtail the whites. That's the critical connection you're lacking, right now.
If the 2 screws on the "hot side" of your switch is still connected by the little tab, it only needs one black wire connected to it - the one bringing power to the switch. If the tab's been broken off and thay are completely independant, then you need to pigtail that black, and connect to both screws.
Making sense, yet?
The other black, that goes to the light, is now a switch leg - like the red is for the fan - it goes on the OTHER side.
...if this still isn't making sense to you, I really think you should call in a pro.