The Prophet Nephi in 2 Nephi suggests four ways to understand Isaiah: know the manner of prophesying among the Jews, have the spirit of prophecy yourself, know the history and geography of the middle east in 700 BC and live in the last days. This timeline and the maps and chart should help you with the big picture.
Recently I completed an adult Institute course on Isaiah, taught by my friend Blair Van Dyke. Blair has worked in the Church Education System for a number of years and the course on Isaiah is one of his favorites.
To begin each class, he sets the stage with maps and a timeline that he roughs out on the whiteboard for his classes. It was always fast and nearly always the same, but I really could not take notes to help you, my readers in Discover Isaiah with Darryl, so I looked into the back issues of the Ensign for resources.
In January 2002, the Ensign offered this great Old Testament Timeline listing major events, prophets, and kings in the Old Testament. You can download it here or view the next few screens to see where Isaiah comes into the big picture.