Creating Production variance

I am testing transactions in the Production module to better understand it.

I created a BOM with 2 backflush component items.

I entered a production order for a qty 1.

The BOM has qty components of 1 each to keep it simple. One of my items is overhead (labor) so one hour of labor for production order qty of 1. Very simple..

I created the production order and released it. Since both components were backflush I then went straight to close the production order. I want to adjust the labor item on the production order because let's say it actually took me 3 hours to produce this production item. Where do i enter the 3 hours so SAP calculates a 2 hour (3-1) variance?