It's impossible to know the private keys for a watch-only address unless you imported the private keys (If that's even possible). Blockchain.info no longer allow you to export private keys for the new HD wallet addresses, there is a way but It's not really newbie friendly , you should check it out though.

Can you help me???

Accidentally i put my wallet addres into import section, and now i can only watch it, and i dont know my private key?