Since Monero is anonymous, you won't see the origin address the funds you receive came from. If you want to know, for instance to credit a particular customer, you'll have to tell the sender to use a payment ID, which is an arbitrary optional tag which gets attached to a transaction. It's not possible to use standalone payment addresses, but you can generate an address that already includes a random payment ID (integrated addresss) using `integrated_address`:
This will generate a random payment ID, and give you the address that includes your own account and that payment ID. If you want to select a particular payment ID, you can do that too. Use:
Payments made to an integrated address generated from your account will go to your account, with that payment ID attached, so you can tell payments apart.