Here is a link to Schoology's help section for setting up grading Categories. It is very good but concise so I provided additional details below if needed. This process only needs to be done at the beginning of a course each semester, or if you have the need to create a new category mid course.
Configuration of Categories from Schoology to Powerschool
The above screenshot displays where one should go to match up your Schoology Categories with those within Powerschool. You can see that Schoology will show all of the Powerschool categories you have created in the PowerTeacher Gradebook (or those already created by the district). When you create at assignment or a Test/Quiz in Schoology you will assign it a Category or Create new grading category and that will add one to these drop down boxes under the Schoology Course Categories. You are able to have multiple Schoology Categories go to the same Powerschool Category. Generally though one would likely keep the categories the same in each to avoid confusion. However, I could maybe have a Schoology category for Vocabulary and one for Worksheet Reviews and link both of them to the Lesson Homework Category if I wanted to. Be sure to click the Save Changes button to save what your have modified.
The Sync Grades tab at the top will open a menu that shows what has been synced and if there are syncing errors with an assignment. You can also click on the sync button to resend info to PowerTeacher Gradebook.
For further questions on setting up these syncing abilities from Schoology to PowerTeacher Gradebook let me know.