The Marks Book dashboard is where you can navigate into an existing Marks Book or create a new one. Once you have done either of those things, you can edit all of the fields in the data selector to your specifications which then presents you with a list of tests that meet the data selector specifications.
Once you have selected the tests you would like to view/input results for, you can customise your view further with the use of filters and sorting preferences. If the cells have a white background then you should be able to simply click on them from this view and input your student data directly. For an annotated help guide on creating and saving a new Marks Book please click here.