Sorry, but you didn't win anything-this is the Nigerian 419 lottery scam. There is no prize-it is imaginary, and the scammer is using the SMS as bait to fool you into sending him your money and details. He will then block your calls, keep your money and steal your identity.
Delete the SMS without replying-it can be used to clone your simcard and copy your phonebook and bank information.
To keep the scammer off your phone, call your network provider and have them block international calls, third-party providers and premium SMS. If this is not available, ignore the calls and delete the messages.