What is the mysqli equivalent of this login code?

Question

I'm trying to do a simple login and I found this code that uses MySQL for that, but my website uses mysqli

I tried to change it myself but crashes the website, is there a mysqli equivalent for this piece of code?

What I want to change

$result=mysql_query($sql);

            if(mysql_num_rows($result)==1){
                echo " You Have Successfully Logged in";
                header("location: menu.html");
            }
            else{
                echo " You Have Entered Incorrect Password";
                exit();
            }

I don't know if this helps, but here is what I have before that piece of code

$server = I;
$usuario = WONT;
$pass = SHOW;
$database= THIS;

$mysqli = new mysqli($server, $usuario, $pass, $database);
            echo "estoy aqui";
            $uname=$_POST['usuario'];
            $password=$_POST['password'];

            $sql = $mysqli -> query ("select * from USUARIOS where usuario='".$uname."'AND password='".$password."' limit 1");

            $result=mysql_query($sql);