Question: Do you have to be sorry for everything you have ever done or just know that you are a sinner and that Jesus is your Savior and want a relationship with him?
In order to be saved, there must be an awareness of your sin and God’s wrath against it. The cross is God’s wrath (righteous anger) poured out on sin. When a sinner becomes aware of his sin, and then becomes of aware that God provided Jesus as a sacrifice for his sin, he is then faced with a choice: receive Jesus’ sacrifice and resulting forgiveness, or reject Jesus sacrifice. You do not have to know everything you’ve ever done wrong (wow, what a list!), but you will be sorry for everything you’ve done wrong.
By the way, all of this is the work of the Spirit. He convicts unbelievers of sin and draws them to Jesus. What a great God!