Install the Arduino IDE (IntegratedDevelopementEnvironment) software.

Get my program(sketch) filefrom the FILES are under $26 Homebrew FS-4.
For the 4-line get the file "FS_4A_4_line.ino"

Double click on its filename and it should open it in the Arduino IDE.
It will tell you it needs to be in a folder of the same name, just say OK.

Up on the top menu bar, click on Tools and pull it down to Manage Libraries.
Use the "Filter your search" at the top right.
Search for I2C LC
Scroll down to LiquidCrystal I2C by Frank de Brabander
click the Install

Now search the Library Manager for "Si5351"
Select the "Etherkit Si5351"
click the install
Exit the libray manager

Now, pull down the Tools menu again.
Pull it down to "Board"  and select "Arduino Nano"

Now, pull down the Tools menu again.
Pull it down to "Processor"  and select "ATmega328P (old bootloader)"

Make sure your Arduino is plugged into the USB.
Pull the Tools menu down to "Port" and select the port your Arduino is on (mine is COM5)

At this point, I think you might have to exit the Arduino IDE via the "X" at upper right.
Now double click on my program .ino file and start up the Arduino IDE again (it needed
to find the new libraries).

Now compile by pushing the "check mark" icon at the top left.
It should compile for a little while and then show the memory usuage in the bottom pane.
If it shows some red compile errors, try to read what it says.. something is wrong.
Ask for help if you can't resolve it.

After you get a clean compile, push the "right arrow" icon at the top left.
This will do a compile again and then load the code into the Arduino.

Now enjoy your FS-4A!