When you log into your FTP space, you will see a directory listing of domains on your account (providing they are on the same server). You will then need to enter into the directory/domain of your choice and upload your files there.
Uploading to the root directory, where you initially log in will not work. This level is beneath what the web can see.
You also need to make sure that you name your main page [color=#CC0000]index.html[/color]. The server picks up on this page as the page to view first into the web browser. If it doesn't find one it will display a directory listing.