If it is a mobile device:
Power and home button at the same time should do it.
If it is a computer:
What kind you you have?
If you have the kind of computer I have (IDK what you would call it exactly but it has a HP on the front. ) If you hold down the windows button and the letter G key a bar will pop up that has the option to record or take pictures. (But that's if you have my kind of laptop.)
If that doesn't work I could meet you in-game sometime and I could take the pictures.