PHP Free & Open Source (most used by web developers i.e
http://facebook.com
JSP & ASP.net (almost same basics)
JSP is build on Java programing language but it is a little but different
ASP.net is build on Basic Programming language
however to obtain the ability to create a web pages you need to learn first HTML (which help you to create the actual web page)
HTML is the layout that you see in browser
other programming languages help you to make dynamic HTML content
there is Javascript that is a popular script language that help you to make effects (dynamic effects) on the client's side
good website tutorials
http://www.w3schools.com