logging in to my forum

I am a bit confused.  Do I log into my forum as an administrator to reply to a post?  And, do I use the same log in as I did here.  My last forum had me logged in automatically as Admin.

Yes.  No this support forum you have a different login.

Do I create a new password for my site log in?  Please explain.

No when you create a forum on https://www.createaforum.com/free-forum.php
That is the login you use for your forum.