Registration key

Hello All,

I have a desktop application in C#(WPF). I have created a setup file for it which is working fine ..but i want to integrate registration key...by which the user first need to enter correct key then only installation can be completed.

i am totally new to it... and its ver urgent...plz help...

For example it should be like when we install windows cd it ask for a key in between,first key is verified then installation continues.


Thankyou.
awaiting for early reply.