For me, forgiveness can enter when I quiet my mind and let the Holy Spirit help me to recognize that there is nothing to forgive. That is, that there is only mind, that the world that I think is a problem is part of the dream, and that all my brothers and sisters are in Truth, are Spirit, the One Son of God.
In practicing the Course, I have learned that if I try to forgive a particular thing or person, then I am focusing on a darkness of and in the dream. One concept in the Course is to not bring the Light to the darkness, but rather the darkness to the Light. So rather than focusing on that particular dark thing or person in the world and wanting and asking for it to be solved, I quiet my mind and ask for Vision as to who I/we really are. There is no world. There is only One Love and One Light.