This is a user-to-user forum. Serial numbers are purchased from Adobe or authorized resellers.
Have you made a purchase?
And CC is licensed through signing into the CC Desktop application, there are no serial numbers.
11091980 if you are being prompted to enter a serial number with your Creative Cloud applications then please see Sign in, activation, or connection errors | CC, CS6, CS5.5 - http://helpx.adobe.com/x-productkb/policy-pricing/activation-network-issues.html.