How do you use WordPress.org? Cant find it…

As idiotic as this sounds, Im trying to familiarize myself with WordPress (the .org version) but I cant even find where it is?
I have carefully installed a local server on my Mac using MAMP.
I have installed the latest version of WordPress in the root folder of that local server.

But now, where is the WordPress interface?

I know this sounds ridiculous, but I have no idea where the actual app is.

I can completely find and use WordPress.com.

People tell me WordPress.org is great.
I just need to know where the thing is!