Sorry, but you didn't win anything, you just received a hoax message to trick you into sending your money and details for a prize that doesn't exist. The scammer will then block your calls, empty your bank account and steal your identity. (Nigerian 419 scam)
Delete the message without replying-it can download malware onto your phone to copy your sim card, phonebook, photos and bank information.
The best way to keep them off your phone is to call your service provider, and have them block international calling, third-party providers and premium SMS. Also check your accounts for unauthorised charges.