Follow these, step by step.
1. Download Zynga Texas HoldEm Poker on you Android/iOS device.
2. Login with Facebook or any other type of account. (Guest/Zynga account)
3. Click on the Settings and chose a REDEEM option.
4. Copy the code and paste, or just type it with Qwerty keyboard.
CODE --> FSM4WDL
P.S: U MUST BE NEW TO ZYNGA POKER AND ATLEAST PLAYED 3 HANDS! and Had the app version downloaded for atleast 3 DAYS! :).