Do you know any programming languages at all? I was able to pick up PHP quickly from the online docs because I already know VB & ASP. The really useful part of the online documentation is the user comments attached to the description of each function. They often describe the quirks, or good ways to use the function.
I personally abhor JavaScript (I realize this isn't what you were asking for). JavaScript has a syntax that is similar to PHP (which is similar to C in syntax). What you need to be familiar with is the DOM (Document Object Model). Most of what you do in JavaScript is to manipulate DOM objects. For example, to redirect the page, you do document.location.href = '/index.htm';. To read a form value you do document.FormName.ElementName.value;.
I assume if you are a designer, you are familiar with the DOM. If that is the case, then you can likely get away with just looking at other sites to see how they do the things you want to do.