Right...because you cannot connect to your database in Dreamweaver you are going to have to update that file when going live or viewing locally.
Locally use "localhost" and live use "hornharmony.fatcowmysql.com"
You should be updating the value in the connections folder.
Once you have it working live. Then update the connection on your local computer and don't upload it again in the future so that your local connection can be different than your live connection information. The same information won't work both live and in DW... you host has told you that.