Frame manipulation

I want to make a page consisting of two frames. The first frame would load the second frame and manipulate its content after finished loading. How can I do this?
I've tried putting this code in the first frame, but no result.

Code:

---

parent.secondframe.onload = function(){ //manipulation here}
parent.secondframe.location = the_url;

---

I've also tried reversing those lines, still no luck. Anybody has suggestion?

If "the_url" is not on the same server as the script, you will not be able to manipulate it. It is a browser security feature.

So that's why.. thanks for the answer.
What I want to do is displaying a page from a url and put some things on top of that page (like text/image) without modifying the page content. Is there any way to do this? Using frame, iframe, div or anything else?

You can do anything you want outside of the iframe containing the foreign URL. However, you cannot access the iframe for information either, probably not even the location.