Blackboard has excellent documentation and videos on the Grade Center.
Check out the Getting Started with the Grade Center document. (8 page pdf)
New in Blackboard 9 -- Color Code your Grade Center
Imagine all grades less than 75% showing up in orange cells! Or color codes for grade status (needs grading, in progress, exempt). Go to Grade Center > Manage > Grading Color Codes > Click on Enable Grading Color Codes and select colors for anything you want to stand out (eg. Needs Grading or scores below 75% on an exam)
Smartviews (video) are limited displays of Grade Center data based on selected criteria. Go to Full Grade Center > Manage > Smart Views
Grade Anonymously! Blackboard allows you to grade anonymously to assure a lack of bias when evaluating student work. (Full Grade Center > head of column > chevron > grade anonymously)
Grade by Questions You can grade all responses to a specific question at once: Full Grade Center > Select column > Grade Questions
Download Grade History (video) Download all grade history to an excel sheet.
Categories and Keywords allow you to insert metadata on each of your test questions to make them more easily searchable when creating new tests.
Import Test or Survey Questions from Excel (video) You can now create questions in an excel file and upload them to Blackboard. Specific formatting is required. Questions can be multiple choice, multiple answer, true/false, or essay.
Create Test Pools (video)
Calculated Formula questions (video) allow you to produce a variety of questions with a range of values so that students will not all get the same answer.
Create a rubric (video) you can now create rubrics inside of Blackboard and associate them with a particular grade center column for ease of grading and student feedback. At present, it does not appear that there is a way for students to view the rubric, so you would need to post a copy of it (possibly a screen shot) somewhere in your course.
Grade Center Tips:
Create a Calculated Grade Column -- set point possible to 0
(this prevents the extra credit from counting against students who don't do it)
Update any Totals or Weighted Columns to include the Extra Credit column.