get name from the user and push it to a stack that is also a .txt file

Question

Like the title says, I have a.txt file with user names (no white spaces but with all sorts of characters). I want to implement it in a stack so users can manipulate it, add(push) new usernames, and pop(remove) already usernames. I'm having problems with the push method, I want to prompt the user for the name and add it to the stack. Should be in a method.

enter code here 

    public static void Add_Username() {

    
    Scanner myScanner = new Scanner(System.in); 

    String line;
    Stack<String> stacks = new Stack<>();
    System.out.println("Please enter the username you'll like to add.");
    line = myScanner.nextLine();
    try {
          File myObj = new File("usernames.txt");
          Scanner myReader = new Scanner(myObj);
          
          while (myReader.hasNextLine()) {
                stacks.push(line);
            }
          myReader.close();
        } catch (FileNotFoundException e) {
          System.out.println("An error occurred.");
          e.printStackTrace();
        }
    
    
}