If you managed to send a file,you've cracked it!Its a year or two since I had to fight Toolpath and I wasn't using it to create programs.I suggest you try not to as well,it is from a very different time and may well have an 8 character file name length limit which was common in the days before Windows 95...
If you can see the files already in the controller you can assume the comms side of things is correctly set up.To send a file you have to select it then go to output-Send-Transmit.It isn't a fast process as I believe it has a 9600 baud rate-again a legacy from earlier times.
When you get to creating your own programs you need to find some software that can post process to a suitable file format I believe.nc is the preferred type but .txt will probably work.

If you have a manual it will tell you how to determine tool length,although they describe it as qualifying the tool.You absolutely have to understand the use of F4 and F8 before cutting anything.If its going wrong then F9 is the function you need.