how can i update the form?if i click on textbox it has to show the all remaining fields?

Hi,

i want to update the form .in the form i am having a combobox like companyname if i selected any one name in the list it has to show the remaining fields.and i can update those fields.how can i proced for this.please do the needful.

for eg:
one customer puchase 3jeans,4tshirts,5shirts in a store.the customer dont want one shirt among 5 already invoice was generated and based on the customer name we have to update the quantity,price and total amount.if i click the customername it has to show the details in a gridview.and those values i have to update.

Best,
Sudheep.