You may want to press F11 to view in fullscreen mode. If you still can't see the whole thing, it's time to change your screen resolution. If the applet doesn't work, it may be time to get Java .
If you want to save your picture, press the "Print Screen" button. Then open up Paint (Start menu->programs->accesories->Paint) and press ctrl+v to copy (Mac users, you're on your own). I recommend testing this before making any fancy pictures.
If you like the program, you can download a version for your computer here . This allows you to automatically save and load pictures, as well as play offline, and it doesn't need any installation. It will probably work on your computer if (and only if) it works above. Just download the program and double-click it. YOu can then save images to any of the 15 save slots. You'll find the images in the same directory as the program.