If you would like to capture the current contents of your iPhone’s screen, be that a game you are playing, a message you are writing or anything else; just hit the following sequence of buttons:
Press the power/sleep button (at the top of the handset) and home button at the same time.
The screen will flash white, and a copy of the iPhone’s screen will be saved as an image. You will be able to find the saved image using the Photos App.