dynamic content - where do i start?

I have a rather simple question. I want to dynamically change the cont开发者_开发问答ent of a based on the selection of a drop down menu. The drop down menu is populated by a php loop that gets data from a mysql database. So far, I'm only familiar with php and html/css.

I don't really know where to start, or more specifically, what technologies I should be researching. So far, I've heard AJAX, JQuery, JavaScript, NOLOH, HTML iframes, pure CSS, etc. I really just want to know where to look!

Start off with the basics: HTML (if you're feeling adventurous, you could try HTML5) and CSS.

After your comfortable with that, you can start getting a little more complex and pick up JavaScript. This is how the majority of the 'dynamic' bits of web pages are accomplished so learn it well.

Once you've got the JavaScript basics down, you can learn how to use JavaScript to manipulate the DOM (Document Object Model) and make AJAX requests back to the server to get new content to insert.