You can access the Grading Types management screen from both your account settings and when creating an assignment.
From your Account Settings:
Select your profile icon located in the top-right corner of any page and go to "Account".
Navigate to your account "Settings" from the left-hand menu and next to "Grading Types", hit the "Manage Grading" button.
From the popup window, Select the "+ Create New Grading Type" button.
Choose your Category, fill out the required fields, and hit "Save".
Your new grading types will be available for all of your assignments in all of your classes.
Please note that grading types are linked to each individual user, and not to an organization.
When Creating an Assignment:
In step 2 of the assignment creation process, select the blue "Manage" button next to "Grading Type".
From the popup window, Select the "+ Create New Grading Type" button.
Choose your Category, fill out the required fields, and hit "Save".
Your new grading types will be available for all of your assignments in all of your classes.
Please note that grading types are linked to each individual user, and not to an organization.