First off, if you do not have the correct version of software, then no matter what you do, you will not be able to read/write to the radio.
For the Icom F50 radio, you need software that is marked 'CS-F50, it only does this series of radios.
If you have the correct software, then plug your cable into the computer, verfiy that the software is using the correct com port, then with radio off, connect the cable to the radio then turn radio on.
Now you should be able to read the radio information, make your changes, save the data, then write to radio.
Simple and easy