Paypal Integration and Return the Confirmation Status for payment or cancel the payment

Question

Hello Guys,

I am in Big Trouble,please Help me out.
i want to Implement Paypal Payment Gateway in my project,Situation is ..If the payment is canceled then it should return some value on my aspx.cs code and if the payment is success then it should also return some confirmation value on code Behind.
value like ...True/False or 1/2 anything but it should return some value.

Please HELP me how can i do that .
its VERY-VERY URGENT !!

Thanks