DataGridView in invoice maker

Question

Hi .. I am new at c# . I am making an invoice generator . In it i am using dataGridView. Its a very new to me. GridView has  4 columns. Item, Quantity, PriceperItem and total. Values in 'item' clumn come from database. and user enters values of 'quantity' and 'priceperitem'. the total value should be automatically generted by calculating quantity*priceperitem when user click on 'yotal' column's cell. I have searched on google alottt but still wondering. I have done something like this but of no value. Kindly help me. Thanks in advance.

public void newFunc()

{

string val;

string val1;

int col = this.dataGridView1.CurrentCell.ColumnIndex;

if (col == 3)

{

val = this.dataGridView1.Columns[1].ToString();

val1 = this.dataGridView1.Columns[2].ToString();

int v = int.Parse(val);

int v1 = int.Parse(val1);

int v2 = v * v1;

this.dataGridView1.CurrentCell.Value = v2;

}

}

private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)

{

newFunc();

}