As a cyoa story, you may interact with the protagonist. Your voices being the passing thoughts in her head. Either asking questions, or making suggestions on what actions to take.
You have the ability, in short. To influence her direction.
However, not though here. As to reduce the spam a cyoa would make. Its hosted on another site called "Waterfall", where it will all be located. In order, neat and tidy in one place. Where you can take part in the story.