some one create my blockchain wallet address with my email id and says to change wallet address password, i change the password and enable 2-factor authantication now he says that put $200 on that blockchain wallet to activate start mining. Its real or scam.
This is definitely scam.
Mining in a pool basically works like this:
1) You buy/build/get an ASIC
2) You give the mining pool your address you want to receive payments to (can be an empty adress)
3) You receive a share to work on (where you will be tryint to solve a challenge from the mining pool operator)
4) You submit your calculated share
5) Whenever someone from this mining pool finds a block, the rewards gets distributed in relation to the % of hashrate you have contributed
Never (under no circumstances) let someone else create a wallet for you.
Always create your wallet yourself. And preferably do not use a online wallet (like blockchain.info).
Visit
https://bitcoin.org/en/choose-your-wallet and read through the differend kind of wallets.