We studied with the LugiatoLefever spatiotemporal formalism the existence, formation and dynamics of solitons in non-linear Kerr micro-resonators. For anomalous and normal dispersion we find different types of solitons, bright and dark respectively. We have determined the region of existence and stability for both types of structures and have studied the introduction of third order dispersion which gives a velocity to the solitons and stabilises them. In the normal GVD regime, we could not find the recently proposed flat top solitons. Ideas why this is the case are discussed.