If you want to apply the visitor visa again, go to contact with the international advisor in your school. They will offer you a list of the documents you need to present to the consulate in Buffalo. As for the payment, I know the consulate in Buffalo accepte money order. You can go to bank and buy a money order with the title to Canada Consulate in Buffalo.
Please check the internatioanl students advisor before you mail the application. I heard currently they require students go to Buffalo to apply visa themselves instead of mailing the application. Be sure you are clear with anything before you mail the application.
Good Lucky!