Before going forward you need to understand how program work on web, you need to understand bit more granular about web level itself than you can probably do now.
Some of this stuff is necessary just to have a more holistic understanding of the ecosystem in which you will be working (and to not sound like a total newbie when talking to other developers about it), but other aspects (like HTTP) will come up again and again when you start programming.
and of course you need to putting yourself in developer shoes. makeup your mind and think in developer prospective, other wise you itself put yourself in cave.
Free your mind and recall your knowledge only for development.
There certain major aspect to understand the Web development:
Q. What is a client and server with example?
Q. What are DNS servers?
Q. What is Design? and what is the impact of this in development? with example (any scenario)
Q. what is the property of Object Oriented Programmings, with example?
Q. What is MVC design pattern and how it works in Web Development, example?
Q.What is HTML and how is it used?
Q.What is CSS and how is it used?
Q.What’s the difference between static and dynamic web pages?
Q.What is Synchronous and Asynchronous call with example?
Q.How AJAX call works?
Q.What is DOM Tree and how you can manipulate the DOM with example?
Q.How the Request and Response works with example?
Q.What is a Java Servlet and life cycle of Servlet?
Q.How Servlet Container serve the Request with example?
Q.What is White box testing?
Q.Give some example of Unit testing?
Q.What is Debugging?
Q.How Debugging works example?
Q.How Web Application Deployment works?
Q.What is a Web server and Application server?