how to go back to previous page in asp .NET

In the webpage, i need a back button which will take us to previous page viewed by the user.
I have tried out the following option,

/****** when i tried this is loading the current page again
String Prev_page = Request.ServerVariables["HTTP_REFERER"];
Response.Redirect(Prev_page);


/******This is also loading the cuurent page again

string prevPage = Request.UrlReferrer.ToString();
Response.Redirect(prevPage);

/******This is throwing exception.
javascript:history(-1)

Please provide me the idea for navigating to prevoius page by clicking the Button

I need C# asp .Net code.