I am using premier, I was trying to find out how to go from a flat black screen to the letterbox opening slowly and to stop at the point I want them, lol It's hard for me to explain, please help.
Go into your effects browser and type in crop. It's a native effect. Apply to your clip and then go into effects control. Keyframe the parameters called top and bottom from 100% to whatever number you want it to end on. How long have you been using premiere?