I have got the unblocking code, how can I unblock iphone 6?

Unblock from what? Where did you get the code? What is the code supposed to unblock?

There is no such thing. I hope you didn't waste any money.

Do you mean unlock?

You need to contact the carrier the iPhone is locked to.

I also hope you didn't pay for it. Only the carrier the device is locked to can authorize an unlock. Anything else is just a hack, and will probably revert back to the lock if you ever update or restore the device. Find out who the device is locked to, contact them about unlocking procedures and see if you qualify.