Disclaimer
Unless you're a programmer or web designer, most users should stay away from this area and use the main customization area, which is designed for anybody to use.
Documentation
Before you jump into tweaking/programming S2, you should understand how it works.
- S2 Documentation -- under construction, but some good content
- Public Layers -- system layers (good reference & place to learn)
Advanced Options
- Your Layers -- create/manage your layers
- Your Styles -- create/manage your styles