How to do Pagination in CodeIgniter

model.php

<?php
class Country_model extends CI_Model {

    public function __construct()
    {
        parent::__construct();
    }

    public function total_rows()
    {
        return $this->db->count_all("apps_countries");
    }

    public function get_countries($limit, $start)
    {
        $this->db->limit($limit, $start);
        $query = $this->db->get("apps_countries");
        if ($query->num_rows() > 0) {
            return $query->result_array();
        }
        return false;
    }

}