# I am not ashamed of the gospel

You can translate this in a positive form. Possible meanings are that 1) Paul is not ashamed of believing the gospel because he knows it is true. Alternate translation: "I am confident in the gospel" 2) Paul is not ashamed of preaching the gospel because he knows that is true. Alternate translation: "I confidently preach the gospel"

# 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.