Accessing mozilla's html document

[Alexey Rodriguez Yakushev]

the main html page of the navigator. Let's clarify: I open my mozilla and go to www.mozilla.org. Then i open my window's application through the task menu. This application draws an html element tree of navigator's html page from which the menu was invoked. For instance the element tree would show the structure of mozilla.org's index.html . Additionally i want to add event handlers. For example if i click on the lizard's nose, i want the appropiate img tag to highlight in the tree. How can i access the main node of the html page and use DOM methods on it? Thanks!! Alexey