how do you unlock your mac if its locked with the find my mac lock

Reset it by, switching macbook off by pressing the power button, boot the computer holding CMD + ALT + P + R Keep holding keys down and wait until the computer beeps twice

If that does not work then off to apple store?

https://discussions.apple.com/thread/3260436?start=0&tstart=0

When locking your Mac remotely, you have to enter a 6 digit code. You would then enter that code to unlock the Mac. Are you saying that you don't remember the code you used? If so, you're going to need to take it to an Apple Store for help, and you'd better have the necessary proofs that the machine is actually yours.

Not that I know of.

"Only Apple retail stores or Apple Authorized Service Providers can unlock computers protected by a firmware password, such as passwords set with Find My Mac."

http://support.apple.com/kb/TS4006

Hi, i just have the same problem with find my mac, i blocked my Mac from iCloud web and when i tried to power on my mac i got a gray screen with a circle with an X in the middle instead of the screen to enter the pin code, so i tried to power on and hold "alt", and when i do that a password field pops up, so i enter de pin code than i use and let me in, but, when i select the osx partition i got a gray screen with a circle with an X in the middle again, so i take a usb with windows 8.1, turned on the macbook pro, hold " alt" , chose my usb, go to windows startup and delete the recovery partition and after that i turn on again my mac and the iCloud block was gone , hope this work for you, and sorry for my bad english.

I need to open my App Store

I don’t anderstand I have a phone