создание новой формы

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
 
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
 
        private void dataGridView1_CellMouseDoubleClick(object sender, DataGridViewCellMouseEventArgs e)
        {
            Form2 f = new Form2(e);
            f.Show();
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
 
namespace WindowsFormsApplication1
{
    public partial class Form2 : Form
    {
        DataGridViewCellMouseEventArgs arg;
        public Form2(DataGridViewCellMouseEventArgs arg)
        {
            InitializeComponent();
            this.arg = arg;
        }
 
        private void Form2_Load(object sender, EventArgs e)
        {
            label1.Text = arg.RowIndex.ToString();
 
        }
 
        private void button1_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}