Very little is written about Abel, however Moses mentioning him means a lot. Abel is mentioned as offering an acceptable sacrifice unto the Lord, then Moses describes how Cain was angry with Abel and killed him. Abel became the first martyr. Jesus mentions righteous Abel some 4,000 years later. The New Testament also talks about Abel.
There are many things that are self-evident about Abel. He was born soon after Adam and Eve left the garden and was killed before 130 years after the fall because Seth was born in that year and Eve declared that the LORD had given her Seth in place of Abel.
It is not unreasonable to believe that Abel lived to be over 100 years of age, a young man compared to many who lived over 900. During those 100 years or so he would have had a family, raised children, seen grandchildren and had all the challenges that life brings.
It is clear that by our fruits we are known, therefore for Abel to be declared righteous he must have lived a righteous life, not just offered one correct sacrifice. It is also clear that he learned how to approach God from his father Adam who knew God personally and was instructed by Him on how the family of Adam could return into the presence of God.
When God spoke to Adam, Eve and the serpent He declared that the seed of the woman would be tormented by the serpent but that he would prevail over the serpent. Thus God declared from the beginning that there would be a Messiah who would triumph over the devil and save the family of Adam from death and hell.
Adam understood this as he taught Abel to make an offering of the firstling of his flocks and to bring the blood and best parts to offer to the Lord. We learn later from Moses that this was a type of the coming Messiah. So from the beginning Adam was taught by God and he taught his children how to worship the Father and honor the Son who would be the lamb slain for the sins of the world and overcome death through his resurrection.
God made it known unto Abel that his offering was accepted. Did he speak to him from heaven, through the Holy Spirit or did he visit him as he visited Abraham, Isaac and Jacob, we are not told but we are told he communicated it to Abel.