AlwaysQuilting

I am trying pp-ing for the first time.
The pattern I downloaded has dark lines and light lines.

I know I'm to sew on the light lines.
But what are the dark lines for?
Am I supposed to cut the pattern apart?
I've googled and watched youtube videos etc but no one says what the dark lines are for.

Here's the pattern:
http://www.paperpanache.com/free/simplereqs/paw.htm

Thanks