Answer 1

I don't have any tutorial to recommend, I prefer to take my time to understand by reading 100 times the same sentence 😑
Anyway I can tell you that in C a data structure is just a specific way to use pointers and structures. So once you learn the language then data structures are all about giving labels to a particular use of the language tools.
Understanding pointers is the crucial part of any data structure manipulation. All your problems will come from a bad understanding of pointers.