To use the emulator, you need Lisa ROMs and Lisa Office System disk images (Office System was the name of the OS). With LisaEm, you can try this piece of computer history. It also implemented document centric approach to using computers.
When it came out, Apple Lisa was a revolutionary machine, and a first personal computer to offer graphical user interface. LisaEm is Apple Lisa emulator that runs on OS X, Windows and Linux.