Google is supporting the Raspberry Pi based education effort with a program called CODER
They have created a Raspberry Pi image with all the tools you need to learn HTML, CSS and Javascript all wrapped in a little web server. This means it’s self contained
, load the image on an SD card
, boot off that card and your on your way. The icing on the cake is that they have put together some great lessons to get you started. To read more, get the download and check out the program in general go to http://googlecreativelab.github.io/coder/