staking will start automatically after a TX got 40 Confirmations + 8 hours to mature... No minimum amount if I'm right but the more you got the higher your weight (luck) and more often staking will happen. Every Stake is at least 0.5 sometimes a bit more from TX-Fees..
@hatientrang as far as I know by reading from other threads around here. BRO is not being traded at any exchange at the moment however, it will soon be added on poswallet. Keep an eye on poswallet in the coming days or so... you will be able to exchange BRO to BTC and vice versa.
Download the wallet, deposit BRO coins into your wallet, Lock your wallet with a password, Restart wallet, Unlock your wallet, but make sure it says unlocked for staking only, then you just keep your wallet online and wait, it may take a very long time to stake coins, depending on how many bro coins you have. More coins = faster staking