By using one of the examples and doing a little reading, I did seem to find what I was looking for. By using the below example, I was able to add a nickname to this list. If the nickname was already there, it would echo something that notified you that the nickname existed and would stop. If the nickname didn't exist, it would write it. So far it seems to have worked cause its not adding the same nickname to the file more than once.

Code:
if ($did == 5) {
  if ($read(files\test.txt,w,$+(*,$did(4).text,*))) {
    .echo -a $did(4).text is already listed.
    halt
  }
  else {
    .write files\test.txt $did(4).text
    .timer 1 1 echo -a $did(4).text was added to the list.
  }
}


By the way I just wanted to say thanks for the help thus far. If there's anything else I may be overlooking feel free to point it out.