How can I add grade a category?

How to set grade a category?

1-    Go to course gradebook from link of the “grades” menu.

2-    On the opened page that click on the “Grader Report” dropdown menu and choose “gradebook setup”

3-    At the new page, click on the “add” link at the right side of the page and choose  “add grade item” in the dropdown menu

4-    You can select a negative value for the "min. grade" in the settings of the item you added