1. Click on the + in the Tasks source list area.
2. Click on New Smart List...

3. Double click on "Complete Date".
4. Leave as "is" or change it to what ever parameters you want for your list.
5. Choose "This week" or whatever criteria you want.

6. Double click on Category.
7. Click on is.
8. Choose a category you want to report on.
9. Click + and repeat until you have all of the categories that you want in the smart list.

If you wanted to restrict this to a certain user, you could add owner in at this time. (See the video)

10. Name the smart list.
11. Click Create.