How to load a url into a frame?

[Adrian]

This may be a really simple problem but I can't seem to figure it out in
dotnet.

Using asp (old style) I had an app that received a querystring on the
server, then parsed out an url from the querystring and sent it back to the
window_onload event on the client. The client in this case is really an
iframe on the browser. I want to dynamically load the content of a page
specified in a querystring inside the iframe. I did this in the past by
using document.location=myurl on the window_onload event of the iframe's
content.

Now I'm trying to port this to dotnet and I find it pretty useful to be able
to put code into codebehind files and use the events that are available in
dotnet, like page_load and so on.

What I'm struggling with is where and how to do the equivalent to what I
described above.

Said another way: is there a simple way in asp.net to askt he browser on the
client to load the content specified by a particular url. The specific url
is determined on the server and sent up to the client???

Thanks
Adrian