new with codeigniter

[eluser]kiga[/eluser]
ey man thanks!!! that was really helpfull!! ... now i pass this and, i'm trying a crud example this is the code for model and controller (both attached) ..

well i follow the instructions for my sql

Database schema. run this script.
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CREATE DATABASE crud;
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USE crud;
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CREATE TABLE tbl_person
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(
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id bigint auto_increment PRIMARY KEY,
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name varchar(50),
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gender char(1),
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dob date
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);
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INSERT tbl_person (name,gender,dob) VALUES('henrihnr', 'm', '1985-09-09');
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INSERT tbl_person (name,gender,dob) VALUES('name_001', 'm', '1990-01-01');
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INSERT tbl_person (name,gender,dob) VALUES('name_002', 'f', '2000-01-01');
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INSERT tbl_person (name,gender,dob) VALUES('name_003', 'm', '2000-02-02');
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INSERT tbl_person (name,gender,dob) VALUES('name_005', 'f', '2000-04-04');
Database configuration. file: CodeIgniter\system\application\config\database.php
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$active_group = "default";
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$active_record = TRUE;
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$db['default']['hostname'] = "localhost";
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$db['default']['username'] = "root";
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$db['default']['password'] = "";
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$db['default']['database'] = "crud";
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$db['default']['dbdriver'] = "mysql";
Base url configuration. file: CodeIgniter\system\application\config\config.php
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$config['base_url'] = "http://127.0.0.1/CodeIgniter/";
Default controller configuration. file: CodeIgniter\system\application\config\routes.php
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$route['default_controller'] = "person";

after all this i try to run mi application and this was te result

An Error Was Encountered

Unable to load the requested class: validation

what i'm doing wrong?

thanks for everything