1 Chronicles
First Chronicles parallels Second Samuel. The author of Chronicles 1 and 2, according to Jewish tradition, is Ezra. Whoever the chronicler is there is little new to be learned as the chronicler appears to have used the earlier books as his major sources of material.
1-29. 1 Chronicles is a list of the generations from Adam to Solomon. It also includes lists of kings, tribes, warriors, attendees at meetings, and a list of people engaged in various occupations from gatekeepers to treasurers. It includes some prayers and poems attributed to David, repeats stories of David's battles and ends with David's death.
2 Chronicles
Second Chronicles parallels First and Second Kings.
1-36. 2 Chronicles begins with David's son Solomon building the temple at Jerusalem. It then describes the ark being brought to the temple on completion, the dedication of the temple, and the visit of the Queen of Sheba. It then repeats stories of later kings, and ends with the fall of Jerusalem to the Babylonians.
With Chronicles being a list of generations and a repetition of stories, I will give a summary here of the Old Testament from Genesis to this point. The Old Testament is a human work with many source documents, authors, and editors. Many of its stories derive from Egyptian mythology and have been remoulded to fit Hebrew monotheism. It is a work of folklore and superstition, and the God that it depicts is - there is no other way to say it when viewed objectively - is a small-minded, homicidal racist. The Old Testament has no more relevance to the modern world than any other ancient text.