pls tell me how 2 use them? as a new player I don't know how to use them that copy button have anything to do with using the gift key?

if u have 3 gift keys ;just copy ur gift keys, and give it to a new player who is like level 4, 5

or if u have a space to enter a gift key, ask from some one who has and paste it or type it there letter one by one and when u add someone's key into ur account you will get 25 000 sm credits

the one who owns the key gets bonus
when the one who add the key(you) complete the levels 5 levels = 5000 SM
10 levels = 15 000 SM and when you complete 15 levels after you add his key; he will get a golden box.