adding a class to HTML using jquery?

Question

I have the following JSFIDDLE, which has a main image and image nav.

I need to wrap a div around the image nav so that i can position it with CSS.

How do i add the class to my HTML?

My Example

Answer 1

the question was not clear to me but you can use wrap

$('img ').wrap('<div class="newClass" />');

http://jsfiddle.net/SgCpq/1/

EDIT

$('img').filter(function(){return $(this).width()===40;})
.wrap('<div class="newClass" />');

http://jsfiddle.net/SgCpq/5/