Everything you need to know is in the project. To take a screenshot in Minecraft, press "F2," and it will save the screenshot to the file called "screenshots" in your Minecraft folder. It's recommended that you press "F1" first, to hide the on-screen GUI. However, this isn't required. (If you can't find your Minecraft folder, try getting on Minecraft, clicking "Texture Packs," and then clicking "Open texture pack folder," you should be able to find it from there). Credit to scratchem for the idea.
