Don't Have an LPT Port That A Program Needs

I have an old Win graphics program that can print only to an LPT port. Neither my compute nor my printer has one.

Can someone tell me how I can foolmy program into thinking that it's printing to LPT1?

Welcome
You need an adaptor.
I am not suggesting any particular store or that you even buy the product shown. I am merely answering your question the best way I know how. I do not endorse this particular product or the store, both are for example only.
Newegg.com - Koutech IO-UP111 USB to Parallel Port Adapter