Simple multithreading, how to run and join?

Request for simple basic multithreading!!
#include

void task1(string msg)
{
    cout << "task1 says: " << msg;
}

int main()
{
   
    thread t1(task1, "Hello");

    t1.join();
}

only thread starting, inputing variables and joining;
My purpose is multithreaded array computing. Not any connections or OOP, all in one function, need pure sample!! please!!!