How to edit this PHP database connection file?

I am very new to PHP, so far I have been using the following schema to connect to a database server and select a database:

mysql_connect("host","username","password");
mysql_select_db("databaseName");

But now I am using some one else's script and it seems to be written in Object Oriented style. So I am at a loss as to how to edit the connection file with my own settings. Suppose my host is "localhost", username is "root", password is "123", and the database to select is "myDatabase" where would I place these in the following script?:

<?php
/**
* MySQL Database Connection Class
* @access public
* @package SPLIB
*/
class MySQL {
    /**
    * MySQL server hostname
    * @access private
    * @var string
    */
    var $host;

    /**
    * MySQL username
    * @access private
    * @var string
    */
    var $dbUser;

    /**
    * MySQL user's password
    * @access private
    * @var string
    */
    var $dbPass;

    /**
    * Name of database to use
    * @access private
    * @var string
    */
    var $dbName;

    /**
    * MySQL Resource link identifier stored here
    * @access private
    * @var string
    */
    var $dbConn;

    /**
    * Stores error messages for connection errors
    * @access private
    * @var string
    */
    var $connectError;

    /**
    * MySQL constructor
    * @param string host (MySQL server hostname)
    * @param string dbUser (MySQL User Name)
    * @param string dbPass (MySQL User Password)
    * @param string dbName (Database to select)
    * @access public
    */
    function MySQL ($host,$dbUser,$dbPass,$dbName) {
        $this->host=$host;
        $this->dbUser=$dbUser;
        $this->dbPass=$dbPass;
        $this->dbName=$dbName;
        $this->connectToDb();
    }

    /**
    * Establishes connection to MySQL and selects a database
    * @return void
    * @access private
    */
    function connectToDb () {
        // Make connection to MySQL server
        if (!$this->dbConn = @mysql_connect($this->host,
                                      $this->dbUser,
                                      $this->dbPass)) {
            trigger_error('Could not connect to server');
            $this->connectError=true;
        // Select database
        } else if ( !@mysql_select_db($this->dbName,$this->dbConn) ) {
            trigger_error('Could not select database');
            $this->connectError=true;
        }
    }

    /**
    * Checks for MySQL errors
    * @return boolean
    * @access public
    */
    function isError () {
        if ( $this->connectError )
            return true;
        $error=mysql_error ($this->dbConn);
        if ( empty ($error) )
            return false;
        else
            return true;
    }

    /**
    * Returns an instance of MySQLResult to fetch rows with
    * @param $sql string the database query to run
    * @return MySQLResult
    * @access public
    */
    function query($sql) {
        if (!$queryResource=mysql_query($sql,$this->dbConn))
            trigger_error ('Query failed: '.mysql_error($this->dbConn).
                           ' SQL: '.$sql);
        return new MySQLResult($this,$queryResource);
    }
}

/**
* MySQLResult Data Fetching Class
* @access public
* @package SPLIB
*/
class MySQLResult {
    /**
    * Instance of MySQL providing database connection
    * @access private
    * @var MySQL
    */
    var $mysql;

    /**
    * Query resource
    * @ac开发者_Go百科cess private
    * @var resource
    */
    var $query;

    /**
    * MySQLResult constructor
    * @param object mysql   (instance of MySQL class)
    * @param resource query (MySQL query resource)
    * @access public
    */
    function MySQLResult(& $mysql,$query) {
        $this->mysql=& $mysql;
        $this->query=$query;
    }

    /**
    * Fetches a row from the result
    * @return array
    * @access public
    */
    function fetch () {
        if ( $row=mysql_fetch_array($this->query,MYSQL_ASSOC) ) {
            return $row;
        } else if ( $this->size() > 0 ) {
            mysql_data_seek($this->query,0);
            return false;
        } else {
            return false;
        }
    }

    /**
    * Returns the number of rows selected
    * @return int
    * @access public
    */
    function size () {
        return mysql_num_rows($this->query);
    }

    /**
    * Returns the ID of the last row inserted
    * @return int
    * @access public
    */
    function insertID () {
        return mysql_insert_id($this->mysql->dbConn);
    }

    /**
    * Checks for MySQL errors
    * @return boolean
    * @access public
    */
    function isError () {
        return $this->mysql->isError();
    }
}
?>

The settings are not in this file. Check for a config file, or maybe a file that creates this object.

If there isn't a config file and you don't have a file that creates this object, you would need to do it manually.

$dbConnection = new MySQL('localhost', 'root', '123', 'myDatabase');

I don't think it is a good practice tough, it would be better if you create a configuration file that return this settings.

What you've posted is two classes. Part of the purpose of a class is to abstract actual values from the code. Therefore, you're going to want to connect to the database by creating an "instance" of the class. That might look like:

$dbConnection = new MySQL('localhost', 'root', '123', 'myDatabase');

After that step, you can do stuff like:

$result = $dbConnection->query("SELECT * FROM `blah`");

You pass this data whilst creating the MySQL class instance:

$db = new MySQL("host", "user", "pass", "name");