As a child of God, you were made righteous by faith - Rom 5:1. You exercised your faith in accepting Jesus as Lord and Savior. Therefore it was by faith that your status got changed. You are no longer condemned but now you have a right standing with God; you have the right to approach God with boldness without fear or condemnation. This is what it means to be righteous.
This change in status was possible because of the sacrifice of Jesus. Jesus became our sins, He died and was locked up in hell for 3 days. Every sin that had been committed and was to be committed in the future was taken care of. Thank God that on the 3rd day, after He had satisfied the claims of justice, He rose up victorious over the powers of the enemy. That victory is ours by virtue of our identification with Jesus. Friend you are already victorious; you must continuously walk in the consciousness of that victory.