Try this it may help u
private void button1_Click(object sender, EventArgs e)
{
DataTable dtToGrid = new DataTable();
DataRow drToGrid;
dtToGrid.Columns.Add(new DataColumn("EMP_ID", typeof(string)));
dtToGrid.Columns.Add(new DataColumn("EMP_FName", typeof(string)));
dtToGrid.Rows.Add();
dtToGrid.Rows[0][0] = txt_empid.Text;
dtToGrid.Rows[0][1] = txt_fname.Text;
dataGridView.DataSource = dtToGrid;
}