Imagine one of the learners in your MOOC, and use the persona template to describe her or him: http://ilde.upf.edu/moocs/pg/lds/new/template/PC. Of course, in reality you will have thousands of learners - but it's always good to have an individual in mind when designing a learning innovation. As we say - If you're not designing for someone, you're designing for no-one.
Think about how participating in your MOOC will change the life of your persona. Tell the story of this change, from her perspective, in her words. Use the "transition matrix" template to do this: http://ilde.upf.edu/moocs/pg/lds/view/2310/ (this time, you will have to click the link that says "duplicate this" at the top centre, and then click "edit this").