How cat can become a friend of baby kitten ?

They can't . They have too grow up togther

Also if you let your cats roam around your house let them smell each other under doors and such thats how i got Pumpkin and Blyu to get along (:

You need to introduce them slowly. Maybe if you feed them close together and play with them together they will get along. Cats are very independent creatures so it may take a while. Put them in a room together under supervision and let the go up to one another. Be sure to watch them as the adult cat may try to hurt the kitten. Again be very cautious and good luck. Ps feel free to ask me questions!