How to install STSoftware forum on WordPress site?

Hello,

I would like to install a forum (by: StSoftware) on a WordPress site… Here is the site I would like to install it to: http://www.chessnoir.com . Don’t worry, I am an admin on the site, I do have the permissions to add it…

But what I can’t do is actually add it. I don’t know how to add it… I would like to put this as the forum: http://www.stsoftware.biz/phpbb3/index.php?style=ca_black but I don’t know how to… I dowloaded the ZIP file from here: http://www.stsoftware.biz/free_phpbb3_styles.html and now I can not install it into my WordPress site. Does anyone know how I can do that?

Thank you! 🙂