Jesus taught us to pray for the Lord to forgive our trespasses (our sins – all our wrongdoing). Everyone should deal with his past. The forgiveness of God is the beginning of healing and organizing the past. Without God`s forgiveness, you are a slave of the past. Praying for the forgiveness of God includes the call for frank examination and daring to see the sad truth, so that afterwards you can see the pleasant side.
God`s forgiveness isn`t cheap. God had to pay a high price for it, which he did. Every time you receive forgiveness from God, you confirm that God hasn`t paid for this in vain. Receiving God's forgiveness makes it possible for you to forgive others. This is how the most important thing you are given in this life is healed - relationships. That's how you get yourself and others out of jail. 

Sometimes it takes a lot of courage to forgive, but it is God's will for you; trust it and take the first step. Forgiveness doesn't start with feelings, but with your decision to show that you want to forgive. It continues with a prayer that God will carry out this decision in you to the end.
Spend time asking for and receiving forgiveness. Make a choice to forgive specific people. Pray that it will come true in your heart as well.