pre paid cellphones

preface: i know nothing about cell phones. i have never used one before. please dont laugh at me. i need a throw-away pre-paid cell phone to use tommorow. just tommorow, so im not looking to waste $ on anything besides a pre-paid phone. i am in canada, will use it here, and want to buy it here. e.g. one of those $100 fido or bell solo phones. i will also need to use it in the united states. can anyone tell me if these phones are capable of working in the united states? thanks. :P