You have now enough knowledge to set up your own simulation in Webots. You are able to design and implement a robot, to setup its controller and to design an environment.
However, the possibilities one has with Webots go far beyond what we have covered here. Reading the documentation related with your application in the User Guide or in the Reference Manual is the first step to extend your knowledge.
The algorithms to develop your controllers are not explained in the Webots documentation. However, another tutorial known as "curriculum" tackles some famous robot programming problems through a sequence of exercises using the e-puck robot and the C language.