How to use Multiple .rs files

first.rs

fn first(){
    println!("{}","From first function");

}
fn main() {
    println!("Hello from first main file!");
    first();
}

second.rs

fn second(){
    println!("{}","From second function");

}

fn main() {
    println!("Hello from second main file!");
    second();
}

cargo run --bin first

cargo run --bin second