Load the DigiUSB→USB2LCD example on to the Digispark with the LCD screen shield connected.
Use the send or monitor programs in the “DigiUSB Programs” folder (included with the download) to send data to the LCD, each line sent gets put on the next line of the LCD (looping to the top) and sending a “¬” - not sign will toggle the backlight.
This should provide quick LCD integration, probably the cheapest USB2LCD solution, and a good jump off point for use of the LCD and DigiUSB libraries.
Newer versions of the Digispark IDE no longer ship with the DigiUSB Programs folder as DigiUSB has been superseded by DigiCDC. For those who wish to continue using DigiUSB the monitor program can still be downloaded from the Digispark GIT repository.