There are several ways to 'right click' on your MacBook. If you do, you can save a picture from the Web using the contextual menu that appears.
1. Hold down the 'control' key while you click.
2. Use a mouse that has multiple buttons.
3. In the Keyboard & Mouse System Preferences under the Trackpad tab, check on the option that says, 'For secondary clicks, place two fingers on the trackpad then click the button'. This is the way I prefer. When you have this option enabled, you can place two fingers on the Trackpad and then simply click the button and the contextual menu will appear.
-Doug