Whether you are offering a 3-week mini-course or a full-length semester class, the process of organizing your content will be the same. You will need to develop the following:

Learner Outcomes (Course Goals).
What do you want the learner to know or be able to do at the end of your course?
Course Overview.
A short written piece explaining the nature of the course and the course goals (a bit like a course description in a course catalog).
The Units Of Study.
This is the course broken down into logical sections with learner outcomes for each unit.
Your Lesson Plans.
The individual lessons within each unit, including objectives, learning activities, and a method for evaluating student mastery (assignments, a paper, quiz, etc.).