So you didn't even update the .htaccess file when you put that rewrite rule into the Permalinks box? Well then, that is another reason why your site isn't working at the moment.
To access your .htaccess, you'll need to access your server with an FTP client first, and make sure that the FTP client is configured to show hidden files. This can usually be set in the preferences or options of the client, so look around. Once you do that, the .htaccess you want to look for is in the root of your WordPress install, or in the root of your server (if you're using the index-in-different-directory trick). If there's nothing there even though you've enabled hidden files with your FTP client, then your server doesn't have a .htaccess yet, so you can just create one.
Either way, you'll want to either open up the .htaccess from your server or a new file in a plain text editor. Then enter in a Permalink structure following the rules on the Permalinks options page. Click the 'Update' button and then a bunch of text is generated in a box. Copy that to the file in your text editor and save it. If you're using a new file, save the file as
.htaccess, that is, a file with no name, but an extension of .htaccess. Then upload that to your server. CHMOD it to something writeable by the server using your FTP client so that when you make further changes to the Permalinks or when you write new Pages, the structure will update itself automatically.