C: Please help! strcpy error

I'm new to programming. I was just fooling around with some code trying to understand how typedef struct works. I used the strcpy function in the code below, because before in my makePerson function i was using the statement person.name=f which returned an error (which I later learnt was because arrays are not assignable in C).

Now I am using the code below, which compiles and runs, but now I'm getting the error flagged in xcode at my first strcpy statement which reads: "Implicitly declaring library function 'strcpy' with type 'char (char, const char *)' "

Can someone please explain what is going on and how I can fix it?

#include <stdio.h>

typedef struct {
    char name[20];
    char lastname[20];
}Person;

Person makePerson(char *f, char *s);

int main(){

    Person Reiad;
    Reiad = makePerson("Reiad","Khan");
    printf("name: %s %s\n",Reiad.name, Reiad.lastname);
    return 0;
}

Person makePerson(char *f, char *s){
    Person person;
    strcpy(person.name,f);
    strcpy(person.lastname,s);
    return person;
}