User blog comment:RowanR/Do you want 5 FREE GEMS?!!/@comment-11654911-20140907144254

In fact;

Step 4: Enter any friend code you want from this page: Friend Codes List and press "Submit"

Probably, that guy just wants you to enter his friend code. Because everytime, someone enters the code he will get 5 diamonds. But you are free to choose any code to submit.