private void button1_Click(object sender, EventArgs e) { if (inputUserName.Text == "") { MessageBox.Show("Field is require"); } else if (inputPassword.Text == "") { MessageBox.Show("Field is require"); } else { User user = new User(inputUserName.Text, inputPassword.Text); GameKids.User.listUsers.Add(user); GameMenu gameMenu = new GameMenu(); gameMenu.Show(); this.Hide(); } }