Locate the lines on the back side of the check labeled "Endorse Here."
Have the person to whom the check is payable print "Pay to the order of X" (where X is your name) in the endorsement area.
Have the person to whom the check is payable endorse the check by signing it directly below "Pay to the order of X."
Endorse the check with your own signature right below the original recipient's signature. The check is now ready for deposit into your own account.