How Can I add a dialog in script?

Hi, everyone,

I have this script:

var myDialog = app.dialogs.add({name:"Tedious Works",canCancel:true}); // <--------- I think can add a dialog in this line but I don't know the syntax
with(myDialog){
    with(dialogColumns.add()){
        with(dialogRows.add()){
           var mySelection = dropdowns.add({stringList:["end digit superscript", "beginning digit superscript", "notes to italic","Initial Cap+ markup","Small Cap + markup","del [ ] + markup","add an EM at beginning"], selectedIndex:0});
       }
   }
}

if (myDialog.show() == true)
   
main();
function main(){
var myObject;
var myCheckSelection = false;
if(app.documents.length > 0){
  if(app.selection.length > 0){
   switch(app.selection[0].constructor.name){
    case "InsertionPoint":
    case "Character":
    case "Word":
    case "TextStyleRange":
    case "Line":
    case "Paragraph":
    case "TextColumn":
    case "Text":
    case "Cell":
    case "Column":
    case "Row":
    case "Table":
     myObject = app.selection[0];
  if(app.selection && app.selection[0].hasOwnProperty ("tedious_works") );
      tedious_works(); 
    }
  }
}
else{
  alert("No documents are open or wrong selection. Please try again.");
}
}
function tedious_works() { 
    if (mySelection.selectedIndex == 0){
   app.findGrepPreferences.findWhat = "\\d$";
   app.changeGrepPreferences.position = 1936749411;
   app.selection[0].changeGrep();
   app.findGrepPreferences = app.changeGrepPreferences = null;
    }
    if (mySelection.selectedIndex == 1){
   app.findGrepPreferences.findWhat = "^\\d";
   app.changeGrepPreferences.position = 1936749411;
   app.selection[0].changeGrep();
   app.findGrepPreferences = app.changeGrepPreferences = null;
    }
   if (mySelection.selectedIndex == 2){
   app.findGrepPreferences.findWhat = "(?i)\\(note.+\\)$";
   app.changeGrepPreferences.appliedCharacterStyle = "Italic";
   app.selection[0].changeGrep();
   app.findGrepPreferences = app.changeGrepPreferences = null;
    }
  if (mySelection.selectedIndex == 3){
   app.findGrepPreferences.findWhat = "（附[註注].+）$";
   app.changeGrepPreferences.appliedCharacterStyle = "Italic";
   app.selection[0].changeGrep();
   app.findGrepPreferences = app.changeGrepPreferences = null;
    }
  if (mySelection.selectedIndex == 4){
   app.findGrepPreferences = app.changeGrepPreferences = null;
   app.findGrepPreferences.findWhat = "\\<a";
   app.changeGrepPreferences.changeTo = "A";
   app.changeGrepPreferences.underline = true;
   app.selection[0].changeGrep();
   app.findGrepPreferences = app.changeGrepPreferences = null;

//...........................not to show too much

I want to add a dialog “please select a tedious works” under the bar, see pic:

please tell me what is the syntax?