I have a web form which shows the different types of items to assemply a PART

As the person selects each item, the numbers are assigned authomatically to create a PART NUMBER for easy ordering (this top part has been created as a frame)
the 2nd part has the regular form to fill out (Name, address, etc) which I created using my webhost webform tool.

When the person submits the form, I get the info from the bottom part (name, address etc) but I can't figure out how to include the info that is pre-selected on the top of the form (PART NUMBER)
Is it something I need to specify on my html file (form)?
I would appreciate if somebody can help me.