You can submit (one or more) picture stories. Each story must be composed of a single photograph and an accompanying narrative (max 250 characters).
Photos
If you submit an image, you do so in accordance with Make History Rules. Make sure you have permission from anyone pictured before submitting the photographs.
Words
Introduce the subject of your picture. Who, what, why, where and when can be a good place to start, but also quotes from those pictured and/or something introspective helps convey the idea.