Simple form to save data to db

All models, controllers and libraries in CI 3.x must start with a capital letter.
In my example:
application/models/Test_model.php
application/controllers/Testcontroller.php

Views are in lowercase:
application/views/test_view.php

If you load a model or library, with $this->load->model(...), then you don't use capital letters.

Information about the differences between 2.x en 3.x is here:
http://www.codeigniter.com/user_guide/in...e_300.html