How to onload?

[Shipi]

Dear Scriptmakers,

I have a PHP based page. I want to onload a javascript in a page but I do not know how can I do that. Let me explain:
My page has an index.php with a slidebar ofc. I always change the content part only. The page what should contain the script is the mainpage.php. I've saved the script in a separated file and I cannot onload it. Is that any way to do that?
This is my script:

<!--
var textarray = [
"hi",
"hello",
"how r u",
"where r u" // No comma after last entry
];

function RndText() {
var rannum= Math.floor(Math.random()*textarray.length);
document.getElementById('ShowText').innerHTML=textarray[rannum];
}
onload = function() { RndText(); }

var inter = setInterval(function() { RndText(); }, 2000);
//-->

And I want to onload here, in the "facts" div. This area is a text contained and image bordered part of the page.

<div id="facts">
	<div class="top">
		<div class="bottom">
			<div class="left">
				<div class="right">
				</div>
			</div>
		</div>
	</div>
</div>

Any help is appreciated!

P.s.: I do not know so much about javascript. And sorry for my English.

[Shipi]

Never mind, I've solved it!