sawbones

I would like to fade or slide between two photos, one 'before' and one 'after.' I have the two images on one canvas, and I can resize and align them so the points of interest overlap very closely. I check this by repeatedly making one of the images visible and not visible so I can see the one on the layer beneath it. My question is, how do I crop these images so as to eliminate the extra edges and make them the same size? Thank you

Sorry, bumping my own post. I haven't figured this out yet. Thanks for any help.

I am a newbie to Designer, and to vector tools in general. I am learning through some great tutorials here, and reading the forum. I have not been able to figure out what might be a very simple issue. I am creating some buttons and boxes with rounded rectangles for a website. I export them to .svg or .png, and then import into Hype, a html 5 program through which I create images and animations. If I trim down the canvas size to closely parallel my button or box in Designer, then export, and then import into Hype, I have a nice transparent background. All is fine. But if I try to apply a shadow or border in Hype, it gets applied to the canvas margins, which are square, and not the image margins. I hope this makes sense, and thanks in advance for your help!