Program to use relays on an Open Source PLC (PLDuino)

I am having a hard time figuring out how to code a simple message turning relays on and off; I am getting errors with my current code. Yes, I have installed the appropriate libraries (or I believe so at least). Here is my code currently:

#include <PLDuino.h>
using namespace PLDuino;

void setup()
{
  // A necessary call.
  // It sets pin modes according to their function.
  PLDuino::init();
}

void loop()
{
  // Simple switch RELAY3 on and off with 2 second timeout.
  digitalWrite(PLDuino::RELAY3, HIGH);
  delay(2000);
  digitalWrite(PLDuino::RELAY3, LOW);
  delay(2000);
}

When I verify, this is the error I get:

"WARNING: Category 'Graphics' in library PLDTouch is not valid. Setting to 'Uncategorized'
WARNING: Category 'General' in library PLDuino-Library is not valid. Setting to 'Uncategorized'
WARNING: Category 'Graphics' in library PLDuinoGUI is not valid. Setting to 'Uncategorized'
Sketch uses 1702 bytes (0%) of program storage space. Maximum is 253952 bytes.
Global variables use 9 bytes (0%) of dynamic memory, leaving 8183 bytes for local variables. Maximum is 8192 bytes.
avrdude: ser_open(): can't open device "\.\COM4": The system cannot find the file specified.

avrdude: ser_drain(): read error: The handle is invalid.

avrdude: ser_send(): write error: sorry no info avail
avrdude: stk500_send(): failed to send command to serial port
avrdude: ser_recv(): read error: The handle is invalid.

avrdude: ser_recv(): read error: The handle is invalid.

avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: ser_send(): write error: sorry no info avail
avrdude: stk500_send(): failed to send command to serial port
avrdude: ser_recv(): read error: The handle is invalid.

avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: ser_send(): write error: sorry no info avail
avrdude: stk500_send(): failed to send command to serial port
avrdude: ser_recv(): read error: The handle is invalid.

avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: ser_send(): write error: sorry no info avail
avrdude: stk500_send(): failed to send command to serial port
avrdude: ser_recv(): read error: The handle is invalid.

avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: ser_send(): write error: sorry no info avail
avrdude: stk500_send(): failed to send command to serial port
avrdude: ser_recv(): read error: The handle is invalid.

avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: ser_send(): write error: sorry no info avail
avrdude: stk500_send(): failed to send command to serial port
avrdude: ser_recv(): read error: The handle is invalid.

avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_getsync(): timeout communicating with programmer"

I'm not sure what's going on here, I'm new with the PLDuino. Thank you so much for the help in advance!

You are getting warnings. Not errors.
But it looks like the main problem is that it is trying to upload the sketch via COM4 and it doesn't find the PLDuino there.

Ok, makes sense. I do have it connected properly so I'm not sure what I can do to fix this. Any thoughts? Thanks!

Anybody have any ideas for this?

Go to device manager and see what ports are being used then unplug the device and see what disappears. Then go into the IDE and pick the port you found to be the one.