For the sake of simplicity, let’s assume we are using Windows OS and have installed Audiveris via the provided Windows Installer available in the Audiveris Releases area. More details are available in Installing binaries.

In this case, we get into the Windows Start Menu, by pressing the Windows logo key on our keyboard or by clicking on the Start icon (left end of the taskbar).
In this menu, we move down to Audiveris folder and select the Audiveris executable.

If we don’t use binary installation, we should refer to Building from sources to build and then launch the software.