This abstract class handles the implementation of the IJob interface. Of course you can override methods.
The work starts with registering your job target in the target registry, and ends with deregistering from the target registry. The entry point is the message handler for the message CRecordStartTarget, which is the first message that the target receives from the system, see "How to start a simple target".
A possible procedure for the implementation of your job target can be found in the tutorial "How to use the job engine for bulk tasks".