MyBB Community Forums

It does not matter where you upload the files just so long as they get uploaded correct? B/c you change the address that you want the forum to be displayed at later on.. Am I correct with that?

Yes, it does matter where you upload the files, since that will be a part of your forum URL. If you upload them into your root directory, that will be your forum's URL. If you upload them into some random directory, THAT will be your URL...so either upload the files into their own specific directory or into your root (if your forum will be the main attraction of your site.)