As a PHP programmer I\'m used to using $_GET to retrieve the HTTP query string... and if I need the whole string, theres loads of ways to do it.
In ASP however, I c
Request.QueryString
returns you a collection of Key/Value pairs representing the Query String. Not a String. Don't think that would cause a Object Reference error though. The reason your getting that is because as Mauro pointed out in the comments. It's QueryString and not Querystring.
Try:
Request.QueryString.ToString();
or
<%
string URL = Request.Url.AbsoluteUri
System.Net.WebClient wc = new System.Net.WebClient();
string data = wc.DownloadString(URL);
Response.Output.Write(data);
%>
Same as your code but Request.Url.AbsoluteUri will return the full path, including the query string.