You need to go to your web server control panel, not VB ACP, to do the URL redirect. You will see options there for the URL redirect
Everyone that lands on
www.yoursite.com will automatically point to
www.yoursite.com/forums or whatever.
Ask your web host provider how to get to the server administration/ CPANEL/root access.
As for FTPing into your site, you need to download something like CORE FTP (freeware) and you can see the files in your public_html directory, but what you need is in the web server control itself. You can also view/edit files from there as well.