Create a short about a minute thirty to two minute video describing a character. Use about 3-5 short clips that describe the characters personality, that portrays what they will be like in the story. Basically you are just taking a closer look at a character before you begin the story so the audience can get to know the characters better.
Make this fun, and interesting, create a story in your blog with this character.
I would recommend using iMovie, because you can do all the editing you need to do within the program, making the overall assignment easier.