please help me to create dialup connection i c#

You may also want to look at the following MSDN site on WinInet:

"Establishing a Dial-Up Connection to the Internet":
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wininet/wininet/establishing_a_dial_up_connection_to_the_internet.asp

This article describes how to interoperate (call unmanaged code from managed code) with the WinInet code from C#:
http://msdn.microsoft.com/netframework/programming/interop/default.aspx

Mike Flasko