We present a classical model to study the formation of charmonia, as well as dissociation and regeneration processes of heavy-quark bound states in the quark gluon plasma using Langevin simulations. The charm and anticharm quarks are described as Brownian particles in the background medium of light quarks and gluons and interact among them over a Coulomb-like screened potential to form bound states, which can dissociate again due to interactions with the medium. Box simulations at fixed temperature and volume are used to verify that the system reaches the expected thermal distribution in the equilibrium limit and to test bound state properties. The medium evolution is then parametrized by a boost-invariant fireball. In this configuration, the elliptic flow of charm and anticharm quarks as well as of charmonia is studied at RHIC and LHC energies.