Custom selection pulldown in QuickCreate portal

I have created a custom pull down selection in the QuickCreate portal after copying the original file over to \local

I can select from one any number of “Show Names” in the list.

Can anyone tell me how I can now save that data as custom field data to search on later. I am thinking the magic has to be done index.html?

The problem encountered is that we must have a custom field in the Quick Create Portlet. Only one is needed but it is important.