主窗体：
public class user{
public void Add_Click(){
    frmClose close = new frmClose(load);
    close.myevent = new UserEdit.TcpStatedelegate
}


public void load(){
    TextBox.Text = "更新成功";
}
}


子窗体:
//定义一个委托以及委托调用的事件
public class UserEdit{
    public delegate void TcpStatedelegate(object sender, EventArgs e);//定义一个委托
    public event TcpStatedelegate myevent;//定义一个上述委托的事件
    public void loadText(){
           user.name = "测试";
          if (myevent != null)//检查事件是否注册
                {
                    myevent(null,null);//调用事件
                }
    }
}