Forgiveness does not create anything new, it simply reminds the mind that what it sees is false.
As such, it is not something to do: since there is no sin in Truth, you are already forgiven. However, the idea of sin needs to be corrected, and that is where forgiveness is useful.
At first, it is believed that something external needs to be forgiven - a person or a situation. If that projection is looked into, it becomes clear that it is our own traumas or beliefs that are causing us to see that person or situation as wrong or difficult. As such, all we ever need to forgive is ourselves.
The most direct way to forgive ourself is to bring to mind a time of struggle, and question the Self that has experienced it as a struggle. When done genuinely and openly, all you find is boundless Awareness untouched by phenomena. The knowing that you are still whole and complete even despite this incident is what allows forgiveness to happen. In fact, you falsely believed that your self is hurt, and as such couldn’t move on.
As long as you do not see what is True, your false beliefs will be shown to you over and over again through repeating circumstances. Forgiveness is natural once you know your own Being. In non-attachment to objective reality, your peace and happiness remain at the foreground of experience.