I tried both with stock Samsung "my files" and the third party app "File Manager". The only thing they let you create is folders so I went ahead anyway and created ".nomedia" but it doesn't work. Can you just tell me step by step so we don't beat around the bush for long?thanks
Download free es file explorer (imo the best file manager).
Or goto some of the existing folders to find one as many apps create this file to hide images used in the their apps.