Learning ERP and BI is not easy task due to vast topics. Not like car test drive, where driver has driving license and car’s cockpit relatively same, ERP is different animal. We divide tutorial based on topic. You may start based on your interest, but it may not a starting chapter, and it’s fine, you can learn on your own path.
For developer you may interest how to develop openbravo ERP or create Pentaho BI content. If you are business user, you can start learn openbravo back office, or learn specific module, i.e payroll module.