How to resize the element style for the text area and manipulate navigation functions , where are th

I want to resize

element.style {

height:173px;

width:956px;

}

to width:600px;

But I can’t since it’s hard coded by this Iframe and I can not over ride it by css

<iframe frameborder=”0″ src=”javascript:true;” style=”width: 956px; height: 173px; “/>

Could you please let me know where is this Iframe and functions concerning Navigation?

I just want to add something in the menu and I didn’t find navigation functions in php files