showing username based on the using machine name in c#

Question

I hosted one webiste in my machine IIS server [Local IIS Server].
For this application we are capturing the cuid [cuid= username,password=password. cuid and password for login to the system active directory] of the system.
If somebody using the application in his machine using my machine IP address.
"http://myIPaddress/BSD_24052013/BusinessVertical.aspx"
then system should show his cuid(cuid=username of his) in his machine.
[who ever accessed application then system should show cuid(username) of the person in his machine]
i need correct post with full information (full code) for this asap.