There are two main types of Course Menu items: a Content Area, and a Tool Link.
Content Area - Used to add text, images, audio and video to your course. You can also include assignments and tests for students to complete in Blackboard. Check out this article for instructions on how to Add a Content Area to a Course Menu
Tool Link - Takes students directly to one of Blackboard's specific tools that you have chosen to utilize in your course. Examples of Tool Links include: Discussion Board, Blogs, or Journals, or My Grades. Check out this article for instructions on how to Add a Tool Link to a Course Menu