I learnt web programming, web application development on my own during college days started with PHP, settled with Python and tried ruby.
How did I learn?
I started with PHP first, writing small scripts and spending time IRC and reading official docs. I attended PHP conference which had prominent minds like creator framwework, Drupal Users etc ...
I created Mini ERP for schools as startup and never launched it.
Then I tried Ruby on Rails and cloned a open source project and modified the source code and fixed bugs (never bothered to submit).
Then I tried Django but wasn't impressed, then I tried Flask and I liked it very much and tried Pylons. Now I am settled with Flask and hacking brubeck occasionally.
Sites I have built:
1. www.sachintweets.in
2. www.iplsaga.in
2. www.pylive.codespeaks.in(currently down)
Web Apps:
1. Gummi - multi user chat room with Flask + Redis
2. Blaze - Static file generator
Takeaway
1. Choose a language and start researching on available web frameworks
2. Attend Conferences.
3. Follow hackers in twitters
4. Subscribe to subreddit
5. Join Mailing list.
6. Use Github and bitbucket.
By creating stuffs which interests you, will answer the question.
In spite of my dislike for Java, I've found a good one (company, that is) and I know how rare they are. If I can stay where I am, I'd rather. But if I'm full-time Java 6 months from now, yes, that is what will happen.