I don't fully understand how to receive payment, there is no Gmail address space, how can I get my address for business transaction, I mean which address will I use to receive payment?
To receive Bitcoin, you don't need a Gmail address or any sort of email address.
What you need is a large random looking number called a Bitcoin-address. This number can be produced from another large number that is kept secret by you and is called a private-key. You can create these numbers using any of many different software programs called Bitcoin wallets.