how can i know forgiveness

The Bible says that if we confess our sins (wrong doings) and are truly sorry than God is faithful and just to forgive us of those sins.  All those who believe in Him will be saved from the ultimate penalty for sin (which is eternal separation from God), and will live with Him forever.

When we believe in Jesus Christ and understand what He has done for us, we are passed from death into life (John 5:24).  The names of those who receive Him are written in the Lambs Book of Life (Revelation 13:8, 17:8).  When those who believe die, we go to be with him forever.

(1 John 1:9&10; 1 Peter 1:2; Ephesians 1:7; Acts 3:19; Psalm 32:5; Proverbs 28:13)