I'm not sure we're understanding this question correctly.

What does the original poster mean by "IE" for a start? "Internet Explorer" or "That is..."?

And we don't know what's mean by "I have two frames".

If you're asking "I want to get code from a website using perl, but the code I want is in a frame whose URL changes every time", it ought to be very simple.

Get the page containing the two frames with LWP::Simple, parse the HTML to find the URL of the second frame.

But the whole thing's a bit of a mystery at the moment.

Please give us more detail and an example.