so many error

[marcuel]

helo guys, can you help me with this eror

Notice: A session had already been started - ignoring session_start() in C:\xampp\htdocs\tricks\Upload\lib\lib.php on line 22

Notice: Undefined variable: prefix_s in C:\xampp\htdocs\tricks\Upload\lib\lib.php on line 25

Notice: Undefined variable: prefix_s in C:\xampp\htdocs\tricks\Upload\lib\lib.php on line 29

the original code is

<?php

/* security*/
  $xHost = $_SERVER['SERVER_NAME'];

  $xReferer = 'http://'.$_SERVER['SERVER_NAME'].$_SERVER['REQUEST_URI'];

  
  if(!empty($xContents)) die($xContents);
  
  //lib start
session_start();

if(!defined('DB_DETAILS')) {
include_once($prefix_s.'lib/lib_database.php');
}

if(!function_exists("set_error")) {
include_once($prefix_s.'lib/lib_functions.php');
}

if(mysql_ver() < 5)
{
set_error("Your server doesn't support MySQL 5.");
}

if(PHP_VERSION < 5.1)
{
set_error("Your server's PHP version is incompatible.");
}

if(!defined('load_gen2'))
{
set_error("We could not load the agent because a request was not declared properly.");
$err_l = true;
}

if(!$c = mysql_connect(DB_HOST, DB_USER, DB_PASS))
{
set_error("We couldn't establish a connection to your MySQL server.");
$err_l = true;
}
if(!mysql_select_db(DB_NAME, $c))
{
set_error("We couldn't establish a connection to your MySQL database.");
$err_l = true;
}


if(!$error_load)
{
DEFINE('START_PROCESS', true);
}

$do->refresh_sess();
?>

[arnage]

Define that var. $prefix_s = './';
And remove session_start() from lib.php on line 22

[marcuel]

what should i change in the code? i am not very good at fixing error in php.

[modfiles]

what should i change in the code? i am not very good at fixing error in php.

seriously, learn at least basic php coz anyone can post a fix in your problem but in the end, still wont work in your side.