Templates are used to define the look and feel of a course. A template determines the layout of the content and interactions between a learner and a course.
When you create a new course, you're asked to choose a template. This template can be changed any time by clicking the icon or the template title next to the course title.
If you change the template, you have to update/republish (click the Update button under Publish tab, or in the Share popup in the top right corner of the editor ) your course in order to apply it to the published version.
To choose the template that fits your course best, apply the template and preview the course. Here are the available templates: