The word genesis means 'beginning' - an appropriate title for the book of the same name. Not only is it the beginning of the Bible, being the first book, it also tells of the beginning of the world and how it was created by God. The Book of Genesis also describes how sin came into the world and how God exercises His judgement, but also His mercy, on mankind.
Genesis 3:17-19
"And unto Adam he said, Because thou hast hearkened unto the voice of thy wife, and hast eaten of the tree, of which I commanded thee, saying, Thou shalt not eat of it: cursed is the ground for thy sake; in sorrow shalt thou eat of it all the days of thy life; thorns also and thistles shall it bring forth to thee; and thou shalt eat the herb of the field; in the sweat of thy face shalt thou eat bread, till thou return unto the ground; for out of it wast thou taken: for dust thou art, and unto dust shalt thou return"