pos system-pole display

I have bought a variety store and have purchased a retail pos system with a pole display that i am having trouble connecting. The model is a vfd450 and the proplem lies somewhere in my ports, I can not get the totals of things scanned to show up on the pole display screen or anything for that matter. The pole must be hooked up to com port 2 but my computer is saying that it can not open com port two and i do not know why. I have two cords going into the pole display as it should when I go into (my computer) and look at the properties and the hardware under ports it says com port 2 is working properly. I downloaded vfd function utility and that allows me to display a demo message on the pole but nothing else. When i go to set com port in the function utility it says my pole is under com port 1 how do i change this, where do i go in my computer to make sure what is suppose to be on com1 is on com 1 and what should be linked to com 2 is linked to com2, how do i change and delete stuff. When the tech set it up for me he said it would work but he has not been any help to me and i am very new to this computer stuff so hopefully i have explained what my problem is well enough and you will be able to help me giving me a detailed answer on what to do as i said i am new, please help