Including <occi.h> in C++ file

Question

I'm trying to include occi.h in my c++ file so I could be able to connect my oracle DB to my program, but it says "cannot open source file occi.h"

How can I fix this issue? I have download and unzipped the instant client, the SDK package, as well as the ODBC files, but I don't know what to do with them. How would I be able to include this occi.h header file?

Here's the code:

#include <iostream>
#include <occi.h>

using namespace std;


struct ShoppingCart {
    int product_id;
    double price;
    int quantity;
};

int main() {

    Environment* env = nullptr;
    Connection* conn = nullptr;

    string user = "username";
    string pass = "password";
    string constr = "myoracle12c.senecacollege.ca:1521/oracle12c";

    env = Environment::createEnvironment(Environment::DEFAULT);
    conn = env->createConnection(user, pass, constr);



    env->terminateConnection(conn);
    Environment::terminateEnvironment(env);

}

Any help would be greatly appreciated, thank you.