Do I have to do anything after I receive my bar code?
No. You can begin using it and printing it on your product right away. Just be prepared to provide it to your retailer so they can add you into their inventory system.
This question often takes the form of "how do i register my barcode", we cover this very misunderstood topic here: https://support.barcodestalk.com/en/support/solutions/articles/16000019158-how-do-i-register-a-bar-code-