0012,
You should be opening the application, archicad, first. The opening splashwindow gives you the choice to open an existing file or a new one.
Please add your version of archicad and computer specs to your profile.
If you still have trouble, reinstall archicad making sure your antivirus is disabled etc.
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"