You need to understand the fundamentals of a web application before diving in. For example, do you understand how a simple form works? How data is transferred from a web browser to a server and back?
I found that the when I was trying to learn the web, I was too obsessed with learning a particular language..rather understanding the basics first, like static html vs server side html, form POST/GET, Css, Js etc.
My suggestion? Write a series of static html pages with css and js. Get a simple page working with a form, then try to submit that form to a server to process.
Once you have a form posting to a server, try generating the entire static html page you wrote on the server side using a simple scripting language (php, asp.net etc)