How do I insert a picture in iMovie '11

I want to have a picture in my project, but the picture is small and you can still see the video. The picture is just something at the bottom or in the corner. Do you know what I mean?

Thanks!

It sounds like you have dropped the picture on top of a video clip, and then chosen Picture in Picture from the pop up menu. You need to drop the picture between clips, where you will see a vertical green line.