You can do many things with .htaccess which is just a simple text file with an odd name, that is located anywhere in the file tree and affects any file or directory "below" it. .htaccess does not have to exist, and must be created when first used. You could place it in the domain.com directory.
An alternate way to dismiss the directory listing of a single directory is to put an empty file named index.html at that location of the path.[hr]
additional thought: .htaccess is typically a 'hidden' file. Make sure your ftp program is configured to show hidden files.