Creating my own classes and saving files

[eluser]Unknown[/eluser]
Hello everyone
I'm new to CI and MVC and I have a couple of simple questions.

First of all, I would like to know if it makes sense to create classes which do not extend a controller nor a model.
For example, I have a model called settings.
I would like it to have a property called mysettings which will be an array of setting object (which is a regular class).
How would I let the model know of setting's class existence? Where would I store it?


Also, I would like to know where would be a good place to save user uploaded files?

Thanks!