Open window on top of the original window

[admin]

don't know too much about java script ;I am using javascript on oracle Portal development tool

I was force to use it on my portal forms;
Here is the scenario:
form FRM1 based on procedure; onClick submit button is getting the value of one field and is opening form FRM2 populating with this passed value;

everything is OK except is opening a new browser window and I dont want this; I want to keep it in the same original window.

I am using :

var URL new string = '.......';

window.open(URL);





Thanks

Lawrence