how do I take a "photograph" of a web-page?

Does this help

• http://en.wikipedia.org/wiki/Screenshot

You can of course always save the web page itself onto your computer. On a Windows computer the keyboard shortcut is Ctlr+S to save a web page. There is also a menu item Firefox Button -> save page as

• Abduction!: https://addons.mozilla.org/firefox/addon/abduction/
• Pixlr Grabber: https://addons.mozilla.org/firefox/addon/pixlr-grabber/

I use "Grab"