The Dashboard has several main navigation areas: (see image below)
The Navigation within the Course is done by menus displayed on top of the content for the course. Keep in mind that you can get back to your Dashboard by clicking on the Dashboard menu item at the very top of the page.
You can open Boxes on each side of the course by clicking on semi-circles located on the top left and right. By default, they are hidden. The box on the left will display every item in your course and the block on the right additional boxes such as the Accessibility block and others you add to it.
You have more options for the course under More... One of the important ones is Course Re-use which will allow you to replicate content from previous courses you have taught.
Here is an example of open blocks in your course:
On the left-hand side:
On the right-hand side:
Keep in mind, you can only open one side at a time. To add a block to the right-hand side first open it and then select the editing mode and then click on Add a Block:
As far as blocks are concerned additionally you can add them to your Dashboard as well by following the same method.