well.... on the actual timeline... you need to go to the part 1 section and click on the upper icon on the right end of the clip.... looks like a square with a stick going from upper left to lower right..... that will bring up a box, which will let you matte the frame in any way you want. what you can do is grab the little square that's at the top/middle of the frame and pull it down... that will narrow the frame. you might want to have the clip overlap/fade over the part 2 section while you're doing this... so you know where exactly to matte it to.