There are two primary methods to add an item to the Gradebook. First, any time you create an Assessment (assignment or test/quiz) or a Participation Activity (discussion or journal) and make it worth points, a corresponding column will automatically be created in the Gradebook.
Second, to create a manual item from within the Gradebook, hover your mouse between any two existing items. A plus (+) sign will appear. Click the plus (+) sign and choose “Create Item." In the panel that appears, type a name for the new column/assignment. Then make it visible to students, and assign a due date, points, and a grade category.
Using the same process, you can also add a Calculated column to your Gradebook. Click the plus (+) sign and choose "Add Calculation." This will allow you to create a calculation to display grades in more than one format (such as Letter, Percentage, Weights, etc.).
See "Can I create a Total Points Calculation" FAQ below for more information.
For more detailed information, view the Navigating Grades Blackboard Help page, under “Gradable Items List."