Add custom field in tier price in Magento

I changed the Magento tierprice preset and configured the file:

app/design/adminhtml/default/default/catalog/product/edit/price/tier.phtml

      

        
        
        
      

    

Data from two new fields ( "cost", "setupcost"

) is successfully displayed on the level page.

How do I insert data into a table catalog_product_entity_tier_price

?
 I want to save this data when clicking the save button of the product page.