What do you mean by debugging a web form with a query string?

If you are using Visual Studio, you can simply debug the form and use "QuickWatch" to see the content of Request.QueryString.

If you want to debug it in WinDbg, you need to know how to place a breakpoint in managed code. In your case, you need to find your page's class and put the break point on the Page_Load function.

When you hit the break point run:

dumpheap -type HttpRequest

it should find the the HttpRequest instance. Then you should run:

!dumpobj XXXX

Where XXXX is the address of the HttpRequest instance.

You should see the QueryString collection member there which you can also see using !dumpobj.

Is this what you were asking for?