Psalm 51:3 For I acknowledge my transgressions, And my sin is always before me.
What is sin? Does it have to be known to you before it becomes sin? No, sin is doing something wrong against God whether you realise it or not.
Knowing that it is sin is the first step. Unless we know God’s laws we will not know whether we are breaking them.
Admitting to the sin is the next step; we could try to live in denial and pretend we are not sinning but we are only fooling ourselves.
The final step is to turn away from that sin. Repentance is embracing all of the steps above and not just one of them. Be honest with God.