For setup Codignitor project.
for setup database
application/config/database.php
$db['default'] = array(
'dsn' => '',
'hostname' => 'localhost',
'username' => 'root',
'password' => ' ',
'database' => 'test',
'dbdriver' => 'mysqli',
'dbprefix' => '',
for setup autoload library
application/config/autoload.php
$autoload['libraries'] = array('database', 'email', 'session');
for setup new routes
application/config/routes.php
$route['default_controller'] = 'welcome';
$route['custom_controller'] = 'custome';