When and how can I cash this savings bond?

I won a $5,000 savings bond from a sweepstakes and want to just cash it in. It just came in the mail, today, do I have to wait a year before I can cash it, or can I pay a penalty and cash it early? I know it will only be half the value if i cash it now, but I need the money now. Also, will my bank do this for me?