First off, there are never dumb questions, the smallest historical questions usually end up being surprisingly insightful and interesting!

As for your question, there were several different types of flashlights used in the Great War. There was the normal 'stick' type flashlight that is common today, though it was a much more primitive and bulky design as flashlights only just became possible in 1899 with the invention of miniature incandescent light bulbs. There were also 'lantern' type flashlights (imagine a box with a large flashlight on the front, held by a handle like one would hold a lamp or lantern) and the German 'Dynamo' flashlight, which was similar to the lantern-style lights but was hung around one's neck like a large necklace instead of being held.

The Dynamo was mainly used by German Stoßtruppen (Shock/Storm troopers) for nighttime raids into enemy trenches, as to not be hindered by needing to hold a clunky light instead of having both hands available. The dynamos were turned on by pulling down on a small chain on the bottom of the Dynamo, which turned the light on for a few seconds.