Tks for your information.
I have tried to follow your instruction to let the job be done. Finally I can do something to put my assigned picture in the category page, however there is huge space under my picture. I can not find which section to revise it. I know it is close to successfully finish it. Advise me how to delete or narrow the huge space.
https://2makimakis.com/wp-content/uploads/2022/09/category-issue.png