There are a few ways to rotate a Photoshop canvas. The first way is to use the Rotate tool. To rotate the canvas, click on the Rotate button and then drag the mouse around the image to rotate it. The second way is to use the Mirror tool. To mirror the image, click on the Mirror button and then drag the mouse around the image to mirror it. The third way is to use the Flip tool. To flip an image, click on the Flip button and then drag the mouse around to flip it.