FAQ: iPhone screenshot
iPhone has a built-in screen grab/capture feature which allows you to effortlessly take a screenshot of any application you are currently using. Here is the simple 1-2-3 do-it-yourself guide.
1. Launch an application or navigate to a web page you'd like to take a screenshot of.
2. Press and hold the round "Home" button at the bottom of your iPhone and then press and release the silver "Sleep" button on the top of your iPhone.
3. Your screen should flash white and your image will be saved to your Camera Roll in the Photos app.