Oracle BPM (ALBPM) quick tutorial

here is a complete explanation of BPMN http://en.wikipedia.org/wiki/BPMN
which describes quite accurately Oracle BPM Studio Graphic Symbols

Business process = defined by tasks and activities
Process instance = a living process

An Activity is conceptually a Step. It can be Automatic or Interactive.
A Transition determines the passage from an Activity to another.

An Activity is made of one or more Tasks

A Role is a job function of a Participant

Flow Objects model Steps in the Process.They can be:
Activities, Gateways, Events, Global Activities, Flow, Lanes, Artifacts