the reason why these forums "skip over" that sort of stuff is because, not to state the obvious really, but phpmyadmin isnt wordpress. It really boils down to that -- the same reason "how to use an ftp client" is more or less skipped over.
The general usage of phpmyadmin is beyond the scope of these forums, and if _we_ went that route, eventually we would be explaining to ppl how to use cpanel, how to use plesk, how to rummage around in mysql from a shell prompt, how to install Apache with php and MySQL onto a LINUX server, how to use any number of ftp clients, how to use windows file manager to find the installed ftp client, etc..etc.. it could go on for days, trust me.
the phpmyadmin web site @ http://www.phpmyadmin.net/home_page/index.php
has their own set of tutorials, a demo set up, and a very good set of documentation.
Additionally, most hosts can direct users to where phpmyadmin is installed, if it is, at all, and give a general walkthrough of how to get there.
Secondly, phpmyadmin isnt necessary for any wordpress install, and not everyone has it available.
Just today, my host upgraded their cpanel, and in addition to phpmyadmin it now looks like I have 2 other ways to access my MySQL databasese.
So its not really one of "the basics" as you say. And its very important for those of us that help here to have a limited scope, even if its rarely enforced. It helps to keep us sane.