You mind posting your code so anyone of us can have a look at it to see what's wrong?

Hi,
Right, Reponse.Write cannot be used since no postback is done…

Since jqgrid doesn't postback to the server.. One option is to use ajax with code handler, or web service.

As for the javascript,

Whenever onSelectRow is called in jqgrid you assigned the ID to the hiddenfield. You don't have to use HiddenField, if you dont know about them you can just use a label and hide it.

However, if you do want to learn more about HiddenField, I suggest you to have a look into MSDN Library.
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.hiddenfield.aspx

Hi,

Is your javascript doing a post back when you select a field on the jqgrid? So the link will be something similar:

localhost:port/Default.aspx?cmd=select&que=0&id=123

Where 123 is the ID selected in the jqgrid.

If that link is displaying and working correctly then you can use querystring on your pageload: