The screenshot in post #1 tells something different.
You did not set the path. You are trying to run hex2bix from your working directory but it's not recognized. You need to enter hex2bix with the full path as in the first call plus the argument, with your work directory being the current directory. Something about "first steps when using the windows (or linux) cmd shell".
To avoid path problems:
* Copy your source file to the hex2bix directory
* use the "cd" command to go to the hex2bix path
* run the hex2bix program without additional paths