This section of Hebrews is known as the Hall of Faith. The writer (no one know for sure who wrote this letter) is trying to show the power of faith. The deeds of so many that we have read about through this summer are down to faith: Noah; Abraham; Sarah; Jacob; and Moses are some of the big names. There are also a few that we didn't read about in our plan.
Abel was the first murder victim (Genesis 4). He was killed by his brother Abel after Adam and Eve, their parents, were kicked out of the garden. The writer says by faith Abel gave the better offering, a bigger sacrifice giving up the first born of his flock than his brothers measly grain. Because of jealousy Cain killed Abel.
Not much is said about Enoch who briefly appears in Genesis 5:21-24. He lived before the flood and so was probably surrounded by the evil and wicked men who prompted God to flood the earth. But Enoch was righteous and is one of only two people who never died on the earth. It says he was taken up to heaven by God. Elijah was the only other person to whom this happened. It was by faith that Enoch walked following God amongst many people who only knew wickedness.
The writer says all of these people earned a good reputation because of their faith in God. But none of these people saw the fulfillment of God's promise. Without ever seeing it they continued to have powerful faith in God. We have seen the promise of God fulfilled and so it should be easier for us to have even more powerful of a faith than the heroes of the Old Testament.