Where do I place my header(.h) files to include in my source code

Hello,

I am going to include my header file I am trying to use, my source code, and the error I am receiving. If anyone could help that would be much appreciated!

Thanks,

-Nick

#include <stdio.h>
#include "stack.h"

int main(){
    Stack s, s1, s2;
    int n;

    //creating stacks
    s = create();
    s1 = create();
    s2 = create();

    //adding numbers to stacks s, s1, and s2
    push(s, 0);
    push(s1, 1);
    push(s2, 2);

    n = pop(s);
    printf("\npopped %d from stack s\n", n);
    return 0;
}

//
// Created by Nick on 4/24/18.
//

#ifndef UNTITLED72_STACK_H
#define UNTITLED72_STACK_H
#include <stdbool.h>

typedef struct stack_type *Stack;

Stack create(void);
void destroy(Stack s);
void make_empty(Stack s);
bool is_empty(Stack s);
bool is_full(Stack s);
void push(Stack s, int i);
int pop(Stack s);
#endif //UNTITLED72_STACK_H

ERROR: 

/Applications/CLion.app/Contents/bin/cmake/bin/cmake --build /Users/nicholausbrell/CLionProjects/untitled72/cmake-build-debug --target untitled72 -- -j 2
[ 50%] Linking C executable untitled72
Undefined symbols for architecture x86_64:
"_create", referenced from:
_main in main.c.o
"_pop", referenced from:
_main in main.c.o
"_push", referenced from:
_main in main.c.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[3]: *** [untitled72] Error 1
make[2]: *** [CMakeFiles/untitled72.dir/all] Error 2
make[1]: *** [CMakeFiles/untitled72.dir/rule] Error 2
make: *** [untitled72] Error 2