Here you can find some general documentation which is useful to understand the SAP Business Process Management.
Before you can use all components of SAP NetWeaver Business Process Management (BPM) you need to perform some initial configuration steps: Configuring Business Process Management.
SAP NetWeaver Business Process Management (BPM) enables you to model, connect, compile, deploy, and maintain composite business processes: Modeling Processes with Process Composer.
SAP NetWeaver Administrator is the central administration tool for the Application Server Java (AS Java). It provides applications for monitoring, configuration, operations and troubleshooting your BPM system: Monitoring and Managing BPM Systems, Processes, and Tasks .
The process desk is a set of user interfaces and functions that enables you to manage processes and tasks and to display details on the process: Managing Processes and Tasks with the Process Desk.
Security issues that are specific to Business Process Management: Business Process Management Security Guide .