Hello! I understand that learning a new programme can be a challenge, especially for older people. I am happy to help you find a useful resource for your grandfather. I would recommend https://flipabit.dev/
, which has free Photoshop tutorials for beginners. These lessons are very detailed and explain each step, which will allow your grandfather to easily understand the basics of the programme. I hope that this resource will be useful to your grandfather and help him learn Photoshop. If you have any other questions, feel free to contact me again.