This should really be a permanent sticky. (Ahem, ok now it is. Thanks!)
Why? Because if someone is willing to pay close to $1000/year for a plugin & themes suite, they are probably willing to invest a bit of time in learning how they work.
To that end, for those who are completely baffled by how the tech behind their site works, there are three links I consider critical for the next three months of your development.
The first course will probably contain a lot of review but unless you are an ace at CSS, you probably want to at least breeze through and pick up the parts you have missed by being self-taught. From there, you will find yourself running up against a wall unless you are a natural coder.
When you hit that wall, use what you know for a while, then watch the videos again from the start. You'll be amazed at how much more sense it makes on the second or third pass.
Be persistent. You need to learn this stuff!
If you aren't 100% clear on what each of these does, here's a good way to think about it.
+ HTML/CSS is what renders a graphical user interface onto your browser. These are the basic building blocks of the web.
+ jQuery is what allows you to manipulate things in a complex way. For example, how do you make a div height exactly the size of the browser window minus the navigation bar? Read on and discover... jQuery is about crafting a more complex UI.
+ PHP is about pulling information out of a data source and rendering it onto the page. In other words, it's how WordPress converts all those MySQL tables into usable data like posts and comments. This has almost nothing to do with layout but everything with how you get the content out of a database, manipulate it, then put it back in.