These pages are, like the archive, a work in progress.
It is not necessary to read all these pages before you start coding! They are intended to be references you can use as you go along. But it's very important that you refer to these documents and read the Front End User Guide and the Coding Standards before you commit any code to the Archive.
If you have only basic experience with HTML/CSS: read the whole Getting Started section below and try out the exercises. You might enjoy writing an archive skin to get started; then move on to the Front End User Guide.
Otherwise: If you do have experience with front end coding, our (and soon your) coding practice may be radically different to what you've done before. Start by reading the Front End User Guide.