How can I solve my error problem when compiling the program? - c

Question

I'm trying to write a car register with different function, in different files, lib.c, lib.h and main.c. However when I try to compile the program it shows this error with my car "unknown type name ‘Car’
34 | void addCar(Car* car)":
In my 'lib.c' file, this is my progress so far:
#include "lib.h"
void printMeny() {
//meny
printf("Meny\n");
printf("1. Lägg till ett fordon\n");
printf("2. Ta bort ett fordon\n");
printf("3. Sortera efter bilmärka\n");
printf("4. Information om ett fordon\n");
printf("5. Skriv ut hela registret\n");
printf("0. Avsluta programmet\n");
}
int getNumber() {
char buffer[10] = {0};
int number = 0;
fgets(buffer,sizeof(buffer),stdin);
sscanf(buffer, "%d", &number);
return number;
}
void getString(char* buf, size_t len) {
if(fgets(buf,len,stdin)) {
char* p;
if((p = strchr(buf, '\n')) != NULL)
{
*p = '\0';
}
}
}
void addCar(Car* car) {
printf("Namn:\n");
getString(car->owner.name, sizeof(car->owner.name));
printf("Ålder:\n");
car->owner.age = getNumber();
printf("Märke:\n");
getString(car->car_brand, sizeof(car->car_brand));
printf("Modell:\n");
getString(car->car_model, sizeof(car->car_model));
printf("Registreringsnummer:\n");
getString(car->plate_num, sizeof(car->plate_num));
}
Then in my lib.h:
//#pragma once
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define CAR_MAX 10
typedef struct {
char name[40];
int age;
} Person;
typedef struct {
Person owner;
char car_brand[20];
char car_model[20];
char plate_num[20];
} Car;
void printMeny();
int getNumber();
void addCar(Car* car);
void getString(char* buffer, size_t len);
And finally in main.c;
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "lib.h"
int main() {
int val = 0;
Car cars[CAR_MAX] = {0};
int numberOfCars = 0;
printMeny();
val = getNumber();
switch(val) {
case 0:
break;
case 1:
addCar(&cars[numberOfCars]);
numberOfCars++;