Hi Amy,
The white highlight you see around the frame shows the actual size of your clip, meaning it's larger than the settings your used for your timeline.
You can quickly fix that by right clicking on the clip and choosing scale to frame size. Or you can get more control by adjusting the scale in your effect control panel under motion controls. You can copy and paste attributes to another clip.
Vince Becquiot
Kaptis Studios
San Francisco - Bay Area