The welcome page page is not in /www. The welcome page is part of the installer - it is displayed whenever the system is started up and some basic ingredients are missing (kernel or site-wide admin accounts, I think). In that case, /packages/acs-bootstrap-installer/installer/index.tcl is displayed. If installation goes successfully, you should see a page like
http://test.openacs.org:8008/, saying "main site", "applications", and "subsites." That page is also not in /www. It's the default subsite home page, /packages/acs-subsite/www/index, which is shown automatically for any subsite (like the main site, which is a special case of a subsite) that doesn't have its own customized index page.
But the important question for solving your problem is, what do you see when you browse to your site?