By selecting the “Course format” you basically decide how your course will be structured. You can access it from the “Settings” tab on the course overview page.
For those in a hurry: Leave the default setting “Topic format”.
In “Weekly format”, set the start date with “Course start date” under the section “General”.
In “Topic format”, your course consists of (automatically) numbered topic blocks. No adjustments need to be made if topics are postponed or canceled.
Set the “Course layout” to “Show one section per page”, for example.
You set the number of topics directly on the course overview page. Remove excess, empty topics or add new ones if required. On the course overview page, the plus / minus symbols fulfill this task.