columns calculated, which sample recommend learn?

hi all my it is my first post .

wich sample see/learn recommend me for: -initially I want a empty table, only headers(Qty/decimal, Description/String, Itemno/String, price/decimal, selected/Boolean or checkbox and Total(calculated qty*price)/decimal -add a row -edit a selected row -delete selected row. -insert a row

not like me this Table: http://www.jonathantneal.com/examples/invoice/

but want calculate(sum) to column: total how do this?(similar to invoice sample).

thanks.