Google App Script to mention discord user via webhook

I am looking to mention a user in a discord channel based on information set in a google sheet.

I have the script already pushing content from the google sheet to the discord channel so know that is working.

I can also get it to use the @everyone tag to mention everyone.

I am now wanting to get it set so that it only will mention the user.

Below is my script so far

function onEdit() {
  var wsID ="  "
  var sheet = SpreadsheetApp.openById(wsID).getSheetByName('discord');

var firestaff = sheet.getRange("A1").getValue(); 
var firecourse = sheet.getRange("B1").getValue();
var policestaff = sheet.getRange("A4").getValue();
var policecourse = sheet.getRange("B4").getValue();
var rescuestaff = sheet.getRange("A14").getValue();
var rescuecourse = sheet.getRange("B14").getValue();


var discordUrl = "", options;

 
var firepayload = JSON.stringify({content: "Please can " + firestaff + " start the " + firecourse + " courses. "
});

var policepayload = JSON.stringify({content: "Please can " + policestaff + " start the " + policecourse + " courses.",
 });

var rescuepayload = JSON.stringify({content: "Please can " + rescuestaff + " start the " + rescuecourse + " courses." });

var policemention = JSON.stringify({content:"@everyone ",


})




var ssurl = JSON.stringify({content: "  "});



var fireparams = {
  method: "POST",
  payload: firepayload,
  muteHttpExceptions : true,
  contentType: "application/json"
};

var policeparams = {
  method: "POST",
  payload: policepayload,
  muteHttpExceptions : true,

  

  contentType: "application/json"
};
var rescueparams = {
  method: "POST",
  payload: rescuepayload,
  muteHttpExceptions : true,
  contentType: "application/json"
};

var urlperms = {
  method: "POST",
  payload: ssurl,
  muteHttpExceptions : true,
  contentType: "application/json"
};

var policemen = {
  method: "POST",
  payload: policemention,
  muteHttpExceptions : true,
  contentType: "application/json"
};



 UrlFetchApp.fetch(discordUrl,policemen)

  UrlFetchApp.fetch(discordUrl, fireparams);
  
  UrlFetchApp.fetch(discordUrl, policeparams);

 
  
  UrlFetchApp.fetch(discordUrl, rescueparams);

  UrlFetchApp.fetch(discordUrl, urlperms);
  


  

}