Click import wallet if you have an existing wallet.
If creating new wallet, set up your password, write it down and store your seed phrase somewhere safe.
Next step is adding BSC network, in order to do it, click on Settings -> Networks -> Add network
Input network details:
Network Name: BSC Mainnet
ChainID: 56, or 0x38 if 56 doesn’t work
Block Explorer URL: https://bscscan.com/
Click on add and your new network is set.
You can toggle between various networks by clicking on top of your wallet.
In order to initiate and pay for any transaction on BSC you need to have BNB in your wallet, similarly to ETH on the Ethereum blockchain.