MyBB Community Forums

Where can I find all my directories such as ./inc/plugins

Through your FTP server.

Do you mean @ my webhost?

Your control panel. For example if you are using cPanel, it would be

public_html >> mybb >> inc >> plugins

*mybb is the folder where you installed your MyBB forum

You need FTP/a File Manager of some kind. Did you install your forum yourself or was it done for you??

From his signature, his forum should be hosted for free. He should consult his forum's support team.

True, but all free hosts should still have FTP unless they're MyBB dedicated, otherwise how would anyone create any files at all??