How to remove the following In the theme

How do I remove the Envied Society

Looks like it is part of or a graphic. Right click on it and check properties. If it is a graphic you can replace it with another the same size. Check with the theme developer for support.

And how do I edit the “Just another…”

That is most likely coming from the tag line. http://codex.wordpress.org/Settings_General_Screen

Finally how do I add my forum link?

You can add a link in the sidebar with a text widget or in your footer.php file using just html.

Maybe you should try a simpler theme to begin with like twentyten. That way you can figure things out in a more friendly environment.