w3schools.com

A excellent references getting start with all languages below:

Grabbed directly from site...

HTML Tutorials
Learn HTML
Learn XHTML
Learn CSS
Learn TCP/IP

XML Tutorials
Learn XML
Learn XSL
Learn XSLT
Learn XSL-FO
Learn XPath
Learn XQuery
Learn XLink
Learn XPointer
Learn DTD
Learn Schema
Learn XML DOM
Learn XForms
Learn SOAP
Learn WSDL
Learn RDF
Learn RSS
Learn WAP
Learn Web Services

Browser Scripting
Learn JavaScript
Learn HTML DOM
Learn DHTML
Learn VBScript
Learn AJAX
Learn AppML
Learn E4X
Learn WMLScript

Server Scripting
Learn SQL
Learn ASP
Learn ADO
Learn PHP

.NET (dotnet)
.NET Microsoft
.NET ASP
.NET Mobile

Multimedia
Learn Media
Learn SMIL
Learn SVG
Learn Flash