For a brief explanation of the gospel, based on the Bible, check out Speak Life's compelling four-minute video, Life According to Jesus in 321. If you want to dig a bit deeper, they even offer an extended course here (free sign-up required).
At its most basic, the gospel is the good news of the Lord Jesus Christ coming into the world to initiate God's Kingdom and to make it so that sinful humans like you and me can be a part of it. God's Word–the Bible–tells us about God, and about His Son Jesus, and about Jesus' loving sacrifice on the cross. Now, each of us is invited to respond to Jesus.
So how do you respond? It can look different for different people. You can pray with a trusted Christian friend. You can go to a Bible-teaching church and pray with a pastor or church leader. You can even pray right now, wherever you are–just bow your head before the Lord and call out, "Have mercy, Lord Jesus. I am a sinner, and I need You. I put my trust in You. Please help me." In whatever way you turn to Jesus, if you do it humbly and sincerely, He will hear you, and He will never turn you away. Now find yourself a gospel-preaching church and discover with others the joy of God's love in Christ!
Please respond to the invitation of Jesus today.