How to create a multi-page plugin

Hi,

I’m a freelance web developer but I’m new here and I’m also new in WordPress development. I’ve launched my first “serious” WordPress website and it also serves me to learn about how to create plugins or themes for it. But today, I come here because I need some help to guide me in how to create a multi-page plugin for WordPress. In fact, I would like to create my own forum for my website… I think that it will be very useful for my users and for my WordPress knowledge. Just to inform, I’ve also developed some complete forums with some frameworks (Symfony 2, CodeIgniter) but I’ve never done this kind of thing with a CMS.

With WordPress, I’ve learnt the bases on how to create a WordPress plugin but I don’t really find a lot of informations on how to create a complete “module” or “plugin” with several pages. Do I have to directly create these pages in my theme folder ? So if I change my theme, I will also have to update my forum files ? Can you help me ?

Thank you very much,
Axel