I am trying to understand the async and await.Now i want to apply async and await keyword in my current project.My process structure are:

//DataAccess  Private List<Users> GetAllUsers() {    .... ;    return List<Users> }  //UI List<Users> UserList=new List<Users>(); private async void Ok_ClickAsync(object sender, RoutedEventArgs e) {     //I want to select all user ant assign to UserList but currently it not use.     UserList=await BindUser();     }  private async Task<List<Users>> BindUser() {   List<Users> model=await Task.Run(()=>GetAllUsers());   return model; } private void btnSave_Click(object sender, RoutedEventArgs e) {    //I want to use UserList here and want to validate process    } 

Problem is if i click save click button quickly,UserList count are 0(Actually UserList record are over 100,000).So I want to check BindUser() process is finish or not before doing validation process in Save_Click(). Please let me known for best solution and help me to understand async and await keyword. Thanks.