Website shows "Index of/"

I am a total newbie.
My website shows "Index of/" and lists a lot of stuff.
Can I get rid of this? How?
I know I've screwed up, and I'm going nuts.
I can't upload anything else to my site.

Any help would be greatly appreciated.

You'll have to upload an "index.html" file, that's the file web-browsers are looking for. If there's no such file, you'll get the "Index of /" listing. In order to upload something, you'll have to connect to the FTP server your hosting company should have told you, and upload the "index.html" to the directory (mostly called "public_html" or just "public") where all the other files are.