The Gospel itself is the fact that Jesus died on the cross for those who would accept him as Savior and Lord. Jesus paid the price for our sins. His death on the cross provided the full payment for every sin that's ever been committed or ever will be committed. We have to consciously accept that free gift of salvation or we don't have it. And once we accept it we need to live like we serve Jesus. Some say that you need to repent at the time of salvation but my experience was that after I was saved I felt convicted of my individual sins over time and I repented of them.