Importing still images from video

I"m new to Toon Boom and wanted to import some still images from video grabs. I exported at 16X9 square pixels from Avid at 864X486. I successfully brought them in under Storyboard/import image as scene, however, the image is cropped in. Do I need to export at a smaller size or do I have to adjust the size to fit the scene 16X9? If I have to resize, how do you do that?Thanks!