When we're walking in the light, there is still sin, but we will also experience Jesus' forgiveness. It's our choice - we can walk in the light that God gives us on the path He shows us, or we can stumble in the dark.
Consider a time, since beginning your walk with God, when you "stumbled in the dark". How did that affect your relationship with God? With others?
How does dealing with our sins as it happens improve our walk with God?
Read 1 John 1:7. Is there a sin your life right now that is affecting your relationship with God or with some person? Confess and surrender that to God right now. If there is something you need to do to make things right with someone else, make a plan to do that right now (be specific and have a timetable so that you will do it!)