[jQuery] Using JQuery in firefox extension

[Lucemia]

hi

I want to know how to use JQuery in firefox extension and have some
trouble.

for example:

$('img').click(function() { alert('hello')}););   // no error, but not
work.

window.content.$('img').click(function() { alert('hello')});); //  it
will raise a error about content.$ is not a function

or

window.content.eval('$("img").click(function()
{ alert("hello")});); // could not use eval

what should i do to make JQuery work in firefox extension?

thanks
lucemia