Open frameset with a GET variable

Hi,

I'm a PHP person, and am having trouble doing something with .NET using C#.

Basically I am opening a framset from a link with a get variable e.g. frame.aspx?id=55

I want the main frame that opens up to call a page using that id number passed in the query string. I have no idea how to do this in .NET (nice and easy in PHP!).

Here's the HTML:

<frameset rows="120,*,15%">
<FRAME src="header.aspx" noresize frameborder="0" scrolling="no">
<FRAME name=Main src="map.aspx?id=63">
<frame name="Bottom" frameborder="0" noresize src="Node.aspx">

I want to substitute the ID in the main frame for the one called in the original link.

Any ideas much appreciated, am totally lost!

Thanks.
</frameset>