The scripture makes mention of the gospel of Christ, which it says "is the power of God, unto salvation to everyone that believeth". (Romans 1:16) To state it another way, anyone who believes the gospel, receives the salvation of God. When the gospel of Christ is believed, it causes the power of God to enter into the life of the person who believes, bringing salvation. All you need to do is believe the gospel and God's part is to release His power in your life to do its work of salvation.
What is salvation? According to Matthew 1:21, when the angel of the Lord appeared unto Joseph, to announce the birth of Christ, the angel said that Jesus would save His people from their sins. Salvation takes care of the sin problem, which every human has.
What is sin? According to Isaiah 59:2, sins comes between man and God, and separate man from God.
Salvation from sins, would therefore mean, that the sins which separates man from God, have been removed and man can now enjoy a relationship and fellowship with God.
Putting the above scriptures together, it means that when the gospel of Christ is believed, the believer of that gospel is reconciled to God.
What therefore is the gospel of Christ? In 1 Corinthians 15, Paul makes mention of the gospel which he preached and which saved those who believed. This he says is the gospel that he preached: "how that Christ died for our sins according to the scriptures, and that He was buried, and that He rose again the third day according to the scriptures. (1 Corinthians 15:3,4).
Believing the gospel is therefore believing that Christ died for your sins, that He was buried and on the third day, He rose from the dead. That is ALL you need to believe and nothing else. If you will believe this gospel from your heart, the salvation of God will enter into your heart.