Question

insert two dashes where needed.
captain john smith one of the first leaders of virginias jamestown colony created a dictionary containing more than five hundred powhatan words, including chesapeake, opossum, persimmon, and raccoon.

Explanation:

The phrase "one of the first leaders of Virginia's Jamestown Colony" is a non-restrictive appositive that adds extra information about Captain John Smith. Non-restrictive appositives are set off from the main clause with a pair of dashes (or commas, but the task specifies dashes). We place one dash right after "Captain John Smith" to start setting off the phrase, and another dash right before "created" to end the set-off phrase.

Answer:

Captain John Smith — one of the first leaders of Virginia's Jamestown Colony — created a dictionary containing more than five hundred Powhatan words, including Chesapeake, opossum, persimmon, and raccoon.