Help:How to import private keys in Bitcoin Core 0.7+
Unlock your wallet
1st you must unlock your wallet.
Open Debug Window
Then go to menu:
/Help/Debug Window File:Screen1.png and click on the tab - Console.
Run Import Command in Debug Window
In the console at the very bottom is a text entry box in here enter:
importprivkey yourPrivateKeyInWalletImportFormat TheLabelThatIWant
Note that this can take a good few seconds and during that time it looks like the client has hung!
Check Key Imported OK
Once Imported you can check that you have the address by closing the Debug window and going back to your address book.
In there you should see the address you imported and the label.