The following video provides an overview of how Unwrella works:

Download video (70 MB, 720*400, MP4 file, H.264 codec)

Download the comprehensive Step-by-Step PDF Tutorial:

Quick Tutorial: Unwrella 2 in 1 Minute
In most cases Unwrella is highly automated, so you won’t need more than a few steps to get your unwrapped UV map.

1. Load your model, apply the Unwrella2 modifier. 

Optionally adjust settings for Unwrella to fit your needs (i.e. texture size, maximum allowed texture stretch), then…

press "Apply"!

Your model is now unwrapped, the seams preserved and all pixels are optimaly scaled.