It sounds like you actually want to learn instead of just implement, so just telling you that HN and Reddit are both Opensource probably isn't what you want to hear.

My suggestion is Ruby On Rails (simply because its what I use and like), it has a very large, helpful community and tons of resources.

The steps I would take (in hindsight), are:

1. Grab the Pickaxe book for Ruby 1.9 and start reading. http://pragprog.com/titles/ruby3/programming-ruby-1-9

2. Do the Ruby Koans - http://rubykoans.com/

3. To get your foot in the Rails door, check out the Rails Tutorial - http://ruby.railstutorial.org/

4. Once you have those basics, check out http://railscasts.com, Ryan has covered just about every problem you are likely to face, and his casts are top-notch!

5. Build something

6. Iterate.

Of course there are other languages and frameworks which would all work just as well, but since it sounds like you don't really have a solid programming background, I think Ruby is really a great language for you to start learning as if there is any language which will keep you interested, its Ruby.