tab bar project, easy to solve

Hi everybody,

I have a problem on Xcode 7, with an iPhone project.

I'm trying to build a tab bar app. I want to have different tab bar items. Navigating in this items, you can push some buttons, who show you others views. How should I write the code of this new view controllers? I tried creating a new Swift file in the project, but i have no idea if I have to create a new controllers-class, or something completely different. Please, help me using a simple language and not too difficult words.

Thanks a lot!