Adding a New column to DataGridView

void MainFormLoad(object sender, EventArgs e)
		{ 
         dataGridView1.ColumnCount=5;
		 dataGridView1.ColumnHeadersVisible=true;
		 DataGridViewCellStyle columnheaderstyle=new DataGridViewCellStyle();
		 columnheaderstyle.BackColor=Color.Beige;
		 dataGridView1.ColumnHeadersDefaultCellStyle=columnheaderstyle;
		 dataGridView1.Columns[3].Name="Date Of Birth";
		 dataGridView1.Columns[3].ValueType=typeof(DateTime);
		 dataGridView1.Columns[3].Width=((dataGridView1.Width)/5)+30;
		 dataGridView1.Columns[1].Name="Employee Id";
		 dataGridView1.Columns[1].ValueType=typeof(string);
		 dataGridView1.Columns[1].Width=(dataGridView1.Width)/5;
		 dataGridView1.Columns[2].Name="Employee name";
		 dataGridView1.Columns[2].ValueType=typeof(string);
		 dataGridView1.Columns[2].Width=(dataGridView1.Width)/5;
		 dataGridView1.Columns[4].Name="Employee Dept";
		 dataGridView1.Columns[4].ValueType=typeof(string);
		 dataGridView1.Columns[4].Width=(dataGridView1.Width)/5;
		 dataGridView1.Columns[1].ReadOnly=false;
		 dataGridView1.Columns[4].ReadOnly=true;
		 dataGridView1.RowHeadersVisible=false;
		 dataGridView1.SelectionMode=DataGridViewSelectionMode.FullRowSelect; 
		}