I cannot get the radio to talk to the computer
The most likely problem areas are
1) The COM port number is not correct. Use the Detect Com port command on the Settings menu to find which values are possible.
2) There is a cabling problem between the receiver and computer. See here for cable type.
3) An unlikely problem is that the transceiver requires a reset to sort out some oddity that has lodged itself in its memory. This should only be done as a last resort - you will lose all of your memories!
The program tries to determine the radio's current baud rate and change it to 38400. It initially expects RTS to be on in the radio but an option on the Settings menu can be ticked to run with RTS off. If you are unable to successfully talk to the radio change the radio's CAT speed to 38400, ensure the RTS state in the radio matches the state in the program and retry.
USB attached devices
If your PC does not have a serial port then you can use a USB to serial adapter and connect a 9-pin programming cable.
Be aware that these USB to serial adapters will be assigned a different Com port number by the operating system for each USB socket that you plug into. You will have to change the Com port number in the program if you use a different USB socket otherwise you will get an error when trying to read/write the radio.