# I am not ashamed of the gospel

You can translate this in a positive form. Possible meanings are that 1) Paul believes that the gospel is true, and he is not afraid of being ashamed for having believed something false. Alternate translation: "I am completely confident that the gospel is true" 2) Paul believes that the gospel is morally good, and he is not afraid of being deceived into doing evil. Alternate translation: "I know the gospel teaches me to do what pleases God"

# it is the power of God for salvation for everyone who believes

Here "believes" means that one puts his trust in Christ. Alternate translation: "it is through the gospel that God powerfully saves those who put their trust in Christ" (See: [[rc://en/ta/man/translate/figs-explicit]])

# for the Jew first and for the Greek

"for Jewish people and also for Greek people"

# first

Here "first" means coming before all others in order of time.