How to Manipulate Images in Pages
If you add an image that appears too large or distorted in your Pages document, you can resize it to correct the problem. Click the image to select it, and then drag one of the selection handles that appear along the border of the image. (The handles look like tiny squares.) A side-selection handle drags only that edge of the frame; the corner-selection handles resize both adjoining edges of the selection frame.
When you hold down the Shift key while you drag, Pages preserves the aspect ratio of the image so that the vertical and horizontal proportions remain fixed.
You can also flip images, a good feature when text or graphics appear backward in your original photo. Click Arrange→Flip Horizontally or Arrange→Flip Vertically to flip the image horizontally or vertically.