Call to undefined function library()

PHP Code:
<?php

class Profile extends CI_Controller
{
    function __construct()
    {
        parent::__construct();
        $this->load->model('M_profile');
    }

    public function index()
    {
        $data = array('data_profile' => $this->M_profile->ambil_profile()->result_array(),);

        $this->load->view('template/header');
        $this->load->view('template/sidebar');
        $this->load->view('dashboard/profile', $data);
        $this->load->view('template/footer');
    }

    function tambah_profile(){
        $this->load->view('template/header');
        $this->load->view('template/sidebar');
        $this->load->view('dashboard/tambah_profile');
        $this->load->view('template/footer');
    }

    function simpan_profile(){
        $id_profile = '';
        $judul = $this->input->post('judul');
        $isi = $this->input->post('isi');

        $config['max_size']=2048;
        $config['allowed_types']="jpg|jpeg|png";
        $config['remove_spaces']=TRUE;
        $config['overwrite']=TRUE;
        $config['upload_path']=FCPATH.'tentang';

        $this->load-library('upload');
        $this->upload->initialize($config);

        $data = $this->upload->do_upload('gambar');
        $data_image = $this->upload->data('file_name');
        $location = 'tentang/';
        $pict = $location-$data_image;

        $data = array(
            'id_profile'=>$id_profile,
            'nama'=>$judul,
            'isi'=>$isi,
            'gambar'=>$pict
        );

        $this->M_profile->simpan('profile', $data);
        $this->session->set_flashdata('sukses', "div class='alert alert-success alert-block'> <a class='close' data-dismis='alert' href='#'>x</a><h4 class='alert-heading'>Sukses!</h4>Data berhasil disimpan!</div>");
        redirect('profile');
    }

}

?>