Copy your private key into a file, eg privatekey.txt

In Linux or Mac, from your Ethereum-Wallet subdirectory, type

    ./resources/node/geth/geth account import privatekey.txt

In Windows, from your Ethereum-Wallet subdirectory, type

    resources\node\geth\geth.exe account import privatekey.txt

In both the above options, you will have to enter a password twice to encrypt your new account information.

You can now start Ethereum-Wallet and the new account will be loaded into the wallet.

**Remember to delete privatekey.txt after you have successfully imported your private key**