I'd recommend going through EST training....

Applied Software (http://www.asti.com/) and/or buying the book their guys wrote some time ago...

https://www.createspace.com/5127316

To add labor to a piece, the content needs a unique database ID. That database ID then also needs to be in the labor table with the appropriate labor added.

There are predefined Labor Rates if you want to apply cost to Labor. 

You can also modify all labor values by a factor, adjusting the base data.

And you can also apply a +/- factor to the values in the table. 

A little complex and a lot of variables to get into here. If you have more question, let me know and I'll answer them as best I can. EST isn't my strongest knowledge base.