the below is 'code sketches', should get you going

1) do not code both serials first time, get one going
2) some of the derivatives with two serials are 'strange' which one do you use
3) No need to start a new thread, but stay here, Steve or Craig will delete the original, I hope.
4) an embedded processor do not return from main() you need to stay there

void main()
{
  // initialize
  ...
  // workloop
  for(;;)
  {
  ....
  }
}

the 'standard way to send data w/o interrupts is
  while (more_data_to_output)
  {
    while (!TI);
    SBUF = next_character;
  }

in an ISR it will be
  if (TI)
  {
    SBUF = next_character;
  }

Erik

ps if "Herr Malund" is a snicker, I am sorry I helped you, if it is extreme politeness, there is no need for that, I sign 'Erik'