Follow the steps below to resize the image on your slide:

1. Click once on the image
2. Small blue 'handles' will appear around the border.  These handles look like little blue squares
3. Move your mouse over one of the handles and notice that your cursor turns into a double-sided arrow
4. Click and drag that arrow in or out/up or down to make the image larger or smaller
5. Once the image is a good size, click-and-drag (in the middle of the image) it to a good spot on the slide.