Can someone clearly explain to me how i can sign my bitcointalk account with btc address.
Thanks.
I'm assuming you aren't speaking about this account as you didn't post any BTC addresses before. First , you should understand that in order to sign a message you will have to control the private keys of that address . In other words , If you are using an address from an exchange or a gambling website or somewhere else then you will probably won't be able to sign a message.
Now If you are using Electrum , Bitcoin Core or Multibit HD as a wallet then the wallets should give you an option to sign (picture taken from Google - Bitcoin Core) :
