I got mail that u won $300,000 for year 2007 & contact to our nigeria location agent so this is true ?

I got mail on 30/5/07 that I won prize for Yahoo Uk & Ireland ? If this is true then where to claim & how to claim tell me ? cause when I got mail from them & I replyed them on their mail which one show in that mail they sent me certifcate & now they required the courier money $200 . So this is true or not ? & tehy gave me phone number of I think african telephone number ? this all r true or making frod with me tel me as soon as possible