Adjust the speed of tween in flash

Click the first frame on the tween (I remember as long as it is the frame on the tween), and the properties of the tween are in the property panel at the bottom. There is a button (I can't remember what it is at the moment, look at it one by one, not many anyway) and the curve panel will pop up at one point. And there are two options, first fast and then slow, first slow and then fast, both in the property panel.