Check out these videos which explain how to do column addition.
https://www.educreations.com/lesson/view/expanded-addition/40628166/?s=QpJu4g&ref=app
https://www.educreations.com/lesson/view/compact-addition/40628228/?s=QjqNmp&ref=app
https://www.educreations.com/lesson/view/carrying-into-10-column/40628388/?s=RLOgnP&ref=app
https://www.educreations.com/lesson/view/compact-carrying-10s/40628498/?s=3uVH7H&ref=app
3ML 