I'm thinking of making a site where people could log-in through forms and post articles and such. How would I be able to do that? What would be the tools required to learn? PHP, Javascript? What do websites such as google, facebook and myspace use?
Before you invent the wheel you may want to check out the existing CMS solutions.
Your time might be better spent learning how to create a custom skin for wordpress, drupal, joomla or one of the many others already out there written by somewhat experienced programmers.
To answer your question, extensive php and java skills.
