Yes, Almarg is right. In the Utilities folder inside your Applications folder is something called Terminal.app. Open it and you'll get a terminal window where you can type command line instructions.
How do I open a command console window in a Mac
I want to uninstall the Hiface program and have the instructions but cannot find where to actually enter the instructions. The Hiface manual says: "Open a console" but the only thing I can bring up (find) is the console log. Help! BTW, I am using OSX 10.5.8 Leopard on an iMac.