I need to write a code in C that make linked list
my professor gave us a three struct
one of them is :

typedef struct classNode
struct classNode *next;
struct genusNode *down;
char name[NAME_LENGTH];
double diversity;

I start to write the program and i dont know how to write a function that make the linked list of this struct
1) i dont know what i need to send to the function
2) the user need to enter the name and the diversity in the function and after that i dont know what to do with those Parameter (name and diversity) !!!

if someone can help me how to write this function i thank him a lot


struct classNode *next pointer to the next struct classNode
struct genusNode *down; pointer to struct genusNode