Creating a timeline to map events of a plot in a story, such as in Rudyard Kipling's The Jungle Book, is no different from creating any historical timeline. We simply draw either a vertical or horizontal line with smaller lines branching out from it. The smaller lines connect to descriptions of events and are used to indicate approximately when the event took place with respect to the surrounding events. You may find the image of The Literature Networks "Literary Periods & History Timeline" to be a useful example.
One thing that can make marking plot events from a story on a timeline tricky is if the story is not told in a linear fashion but rather through flashbacks. Luckily, Kipling's story in The Jungle Book has a very linear progression, starting with Mowgli's adoption by Mother Wolf and ending with Mowgli's decision to say goodbye to the wolf pack and join the race of humans. There are also no dates given in the setting, which makes your task easier since you only need to name events and place them in a proper, organized order in your timeline.
Depending on how detailed your assignment needs to be, it will most likely be easiest and only necessary to identify the main events in the timeline. Events to consider for Book 1 include Mowgli's adoption into the wolf pack despite resistance from the other jungle animals, especially Shere Khan, the ruthless tiger; Bagheera, the panther who once lived in captivity, teaching Mowgli the Law of the Jungle, to fear Shere Khan, and that he must someday return to live among the men; and the moment Shere Khan feels he has the right to ask to kill Mowgli because it was time for the elderly Akela to step down as leader of the pack.