Bellu on "Split Plugin code on multiple pages"

I'm developing a little plugin and i want to split the code in multiple pages.
At the moment i have only one PHP file in my plugin's folder.
I need to split the plugin like i can do when i develop a wordpress template.

I need something like this:
- my plugin folder
->my-plugin-main-file.php
->my-plugin-single-item.php

How can i define this?

Sorry for my english and thank you for helping me.