It depends on the LED screen.
Does it have an interface?
If so, what is it? If it is USB, then the chances are it came with software to control it anyway, or such is available from the manufacturers website.
If it is serial, then it is older, and may be available from the makers.
If it is parallel, then the chances are you need to do it all yourself: but there is an article here which may help:
I/O Ports Uncensored - 1 - Controlling LEDs (Light Emiting Diodes) with Parallel Port[
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