HELP ME PLEASE.

[DonOmar]

Hello guys i wanna Ask for Something . i have made a code for my groups system but i want to do something in this code

function leaveMyGang() 
    if (confirmSaleWindow) then return end 
    local width, height = (screenWidth-311)/2, (screenHeight-137)/2 
    confirmSaleWindow = guiCreateWindow(width, height, 311, 137, "CIF Groups", false) 
    guiSetAlpha(confirmSaleWindow, 0.95) 
    guiWindowSetSizable(confirmSaleWindow, false) 
  
    notEnoughLabel = guiCreateLabel(14,32,286,66, "Are you sure you want to leave your group?", false, confirmSaleWindow) 
    guiSetAlpha(notEnoughLabel, 1) 
    guiLabelSetVerticalAlign(notEnoughLabel, "top") 
    guiLabelSetHorizontalAlign(notEnoughLabel, "left", true) 
    guiSetFont(notEnoughLabel, "clear-normal") 
     
    okSellCar = guiCreateButton(75,84,71,36, "Yes", false, confirmSaleWindow) 
    addEventHandler("onClientGUIClick", okSellCar, function() destroyElement(confirmSaleWindow) confirmSaleWindow = nil triggerServerEvent("gang.leavegang", localPlayer) end, false) 
     
    noSellCar = guiCreateButton(170,84,71,36, "No", false,confirmSaleWindow) 
    addEventHandler("onClientGUIClick", noSellCar, function() destroyElement(confirmSaleWindow) confirmSaleWindow = nil end, false) 
end 
  

i wanna make a Message box to leave a Reason before leaving the group.