I think you’re confusing something here. Your account on the domain wordpress.org (where this forum exists here) has nothing to do with your local installation of WordPress. You have to set up and use your own login in your local installation. In the local installation of WordPress you will be asked to enter a username and password. This is exactly what you need to use to log in to your local install.
Thank you very much for answering but I need more help please.
I want my friend to be able to edit my site, the problem is I am using local host and he’s on PC, and so he’s unable to log in to my wordpress.org site.
Also, just to make sure… will I be able to make my site public for everyone to see in the future, even people that dont have local host?
If two of you want to work on the project, it would be better to host it. There are many WordPress hosting options. You can find some here: https://wordpress.org/hosting/ – this would solve your problem immediately and quickly. This is actually how almost everyone who uses WordPress together with others works.
If you don’t want to book a hosting package, you can also try to make your locally installed WordPress available on the Internet. I don’t know how this works on a Mac. Technically speaking, however, the Mac has to be permanently on and have a stable Internet connection. Since this isn’t really an issue for WordPress itself, I would recommend that you get information about it in a Mac community.