This is my teaching. It is only for one thing, suffering and how to end it.
The first truth you must understand is this, All Suffer. Birth is suffering, decay is suffering, death is suffering; sorrow, lamentation, pain, grief, and despair are suffering. To be separated from the pleasant is suffering; to be in contact with the unpleasant is suffering; in short the five aggregates of existence connected with attachment are all suffering.
Secondly. The cause of Suffering is craving but at the root cause it is ignorance. The objects of craving are manifold: sensual pleasure, material possessions, glory, power, fame, ego, craving for re-birth, even craving for freedom from these things. There are various degrees of craving from a mild wish to an acute grasping. Craving is the proximate cause of suffering and is itself caused by other conditioning factors. The full formula of causation can be traced back, back to ignorance.
The Third Truth is the following. That the cause of suffering can be counteracted.
This is the key. Suffering is born of craving which itself is born from ignorance and so it can be ended. Your suffering can end.