Ive recently been trying really hard to get my head around Wordpress, but so far Ive had several false starts. I think Im being quite dumb and theres some fundamental concepts Im just not getting and I've been banging my head against the wall for too long! So I thought Id come to you guys for help. Ive gone through so many tutorials and tried to read around it but getting totally lost!

Im still quite new to web development, teaching myself. Have a good basic grounding in html/css and I've made a start with php recently.

The best way to explain my problem is to lok at the tutorial Ive just been following, to build my own basic custom theme. You can find it here:

http://www.onextrapixel.com/2011/03/...-from-scratch/

The tutorial provides all the basic code needed to build a simple theme template. Im tinkering around with it. When I go into style.css to edit some styles, I notice various class selectors for the navigation ('.nav' for example). The I realise....where did the class name come from? I cant find any mark-up in any of the php files that contain any html with the "class=nav" in them for the main navigation. I can find a 'navigation' class in the index.php file, but nowhere a .nav.

I dont like altering my css without seeing the markup its relating to! Please tell me what Im missing/not understanding.

Thanks!