The basic idea of the site is for users to create a character and create art and / or a background story to go with the article, as mentioned in the introduction a combination of art and back story is not essential; a member can upload an image with a headline and challenge others to write the background story or you may wish to publish a story and one of the artists among us can create an image(s) to go with the story.
As for your character, they can be whatever you like as long as they fit in with the various canons as described in the "Tour" section of the site.
The same is true for any news, it should fit within the timeline and current state of the universe which can also be found in the "Tour" section of the site.
Read more: How Does It Work?