Suppose the book you see here is a record of every thing you've ever done in your life. Each page is filled with details about all the sins you've committed on each day. Everything that you've said, thought, done or even things you didn't do that you knew you should have are recorded in this book.
Now you want to go to Heaven and live eternally with God but because God is Holy He can't have sin around Him. So you can't go to Heaven in the sinful state that you are in. You see God loves YOU but hates your SIN.
So what God did was come down to earth and live the perfect life for us since we can't possibly be perfect ourselves. The Bible says Jesus was 100% man and 100% God, He was the infinate God/man. He lived among us and was tempted just as we are. But He never sinned.
Then He went to the cross for us. The Bible says they beat Him, mocked Him, and put a crown of thorns on His head. Then they nailed him to a cross and left Him there to die. But that was God's perfect plan for us. Jesus died so that we may live. He took the punishment that we deserve because of our sins. God poured all His wrath for our sins on Jesus. Jesus paid the debt for our sins in full on the cross. When we try to work our way to Heaven by doing good deeds we are trying to pay for something that is already paid for. What God asks of us is to accept that payment for our sins and trust Jesus as the only way to eternal life.
Jesus says in John 14:6 "I am the Way, the Truth, and the Life, no man comes to the Father but through Me." Make a decision to ask Jesus to forgive your sins and follow Him.