How To Pass Values Into The Parent Form

i have a drop-down menu with a list of products.when i select any one
product i open a popup displaying hte product categories in it.i then
enter the no. of items i want.and finally when i click to the submit
button i want to display a summary of selected item in the parent
form.to make it more elaborate:

i have 3 items in a drop-down menu and each item has further 10
different types of products.

something like u have an item soap. and then 10 different brands of
soap.so all my products are in the drop down menu in the parent form.
item 1
item 2
item 3
item 4

when i select item 1 i get a popup menu which has say 20 types of item1
from the database.i generate textboxes beside each label so that user
can enter his quantity. Code: