Your contribution will become part of the file. This could cover a range of possibilities from calling attention to the way a work is composed or constructed, its use of the medium, the way it relates to other works by the artist or by other artists who were doing something similar, how it fits in to some kind of chronology etc. All of these ideas can be illuminated by links to other images, websites, information etc. These might be widely recognized symbols or markers of status, gender etc. Could you see it as relating to images of work, leisure, Native Americans, women, domestic life, settling the West, views on relations of people and the land, religion, etc.
Some museums have special websites presenting material for children.