Kim, the best way to keep your images from being used is to size them to fit your intended use. A residual benefit is that they will load faster if they are small. Internet browsers download everything they display. It is possible to turn off right click in the page code, however, since the image has to be downloaded, it can be picked up from cache if you know where to look. Print Screen will also collect the image to the clipboard, as it appears on the monitor.
Let your friend know you would like the page to work with phones as well as computers and see how it turns out. Best wishes for a successful project.