Port problem

Question

I have a program that allows me to write things to a Pocket PC through the com ports. But on the Pocket PC I received today, there were only a USB cable for connecting it to my PC. How can I do similar things through a USB port? Are they named as com ports also, and if so, what are the usual numbers? I have an Acer Ferrari 3000 laptop, with 4 usb ports..... I want to be able to send data to the Pocket PC through the USB port of my laptop, to learn how to handle incoming data. Thanks.