I was in a forum searching for an answer on how to find and edit a particular part of a CSS file  and i stumbled on the firebug . Simply put, this firefox addon is one of the best experiences for any web developer, all you need to do is simply download it from the site, then after it as been installed you would see the great difference it will make in your developing experience.

To access  firebug after it has been installed, please go to tools and then click on firebug to open up.

Practically just open up any webpage you would like to take a look at the codes, then go to tools and open up firebug, you would immediately see the a new window with options of viewing html,  css and DOM. If you are good with your browsing, it wouldnt be that hard to get around. It will even indicate what part of the site any code you see on the firebug is associated with. Please read an extract from firebug below.

"Firebug integrates with Firefox to put a wealth of development tools at your fingertips while you browse. You can edit, debug, and monitor CSS, HTML, and JavaScript live in any web page..."

Hope this helps.