you really had 2 questions, how to set up shipping and how to have eCart create the order table automatically, I needed clarification on the shipping question, but tried to address the creating the order table question. 2 is the second step to follow to have eCart create the order table.
The UPS Shipping rate lookup takes the height Width and depth of the package to ship.
you can either set it up to calculate on an item by item basis, not really recommended, or to ship the entire order in one package.
If you set it to ship the entire order in one package, you dont need to provide package dimensions until you run the checkout wizard.
In the checkout wizard, you will be able to specify UPS as your shipping provider, and set the package dimensions to use.