Here are few ideas about how to forgive.
1) Perfect forgiveness comes through Jesus, who compensated for the offenses we committed against Him by sacrificing His own life. In order to forgive, we must, therefore, surrender our will to God by desiring nothing except to do and accept His will.
2) Sacrifice our hurt and pride, just as Jesus humbled Himself and sacrificed His life for us, in order to bring forgiveness and healing to those who offend us.
3) Constantly remember that we are sinners who are forgiven by the sacrificial body and blood of Christ.
Please feel free to add some more.