Forensic Fonts (TM) is a program designed to allow the digital forensic examiner to more clearly see precisely what is present in a trace. In particular, FF takes a byte sequence from standard input and displays it in a graphical user interface in such a manner that the user can see both the displayed content and the byte value for each byte present. For full details, look here
In each case, make sure you are in the proper directory to run FF and that you type the proper path for the filename.