I think he/she meant to create a repository class.

Your controller would look something like

<?php

use Vanpet\Repositories\AgendaRepositoryInterface;

class AgendaController extends Controller {

    protected $agenda;

    public function __construct(AgendaRepositoryInterface $agenda)
    {
        $this->agenda = $agenda;
    }

    public function show($year, $month, $day)
    {
        if($this->agenda->findByDate($year, $month, $day, Input::all()) {
            return View::make('agenda.show', $agenda);
        } else {
            return View::make('error.page');
        }
    }

and then in your repository you would do all the stuff necessary to return the correct angenda(s)

Above might be a lot of info for a beginner but let me know if it makes sense.