Yes i have the private key. in AES format
And where i type bitcoind importprivkey WIF_KEY false ?
You'll need them in unencrypted format. The easiest way to get them is to log into Blockchain, go to Import / Export, then Export Unencrypted, and finally choose Bitcoin-Qt format. The private keys are the text that come after each "priv" element, and usually start with a 5 (but might start with an L or K).
If you're running the "normal" graphical version of Bitcoin, you can go to the Help menu, choose Debug window, and then click the Console tab. You can type the importprivkey commands into this window. For an example, type in: help importprivkey
Edited to add: it's much safer to simply send your Bitcoin from Blockchain to you desktop wallet. The problem with exporting/importing is that you're dealing with unencrypted keys, which might get saved to the browser's cache for example, and might get later stolen by malware. It may sound far-fetched, but as they say, "better safe than sorry."
