Design your model class that extends LAbstractRSModel and implements ContextBuilder. The build() method should create agents and add them to the context(s).
Schedule the a method that calls super.step() fill the method getAgentIterable() that returns an Iterable over your agents. Calling the methods of the agents does LAbstractRSModel for you.
Basically, the LAbstractRsModel instance of the model registers the methods stepIt() and finish() at the Repast Simphony scheduler to be triggered at every step and at the end of simulations respectively. These methods publish LModelStepEvent and LModelFinishEvent respectively.
The initialisation of LARA is rooted in the build(Context) method of your instance of LAbstractRsModel.