Step 2: Assemble pieces
Grab the ears you want to add (and if you want a ruff, that too), and any spines or such.
Locate where the pieces want to be (spines go at Center Ridge, ears go at Ears, and ruffs go across Ears as well).
You'll sew the like-color edges together (red edge to red edge, blue to blue.)
Make sure you sew the ears and stuff in place as you sew the edges. You may wish to pin these things in place before you start sewing.
REMEMBER: You are sewing this hat inside out, so please make sure your ears and stuff are placed correctly so that when you finally flip the hat right side out, they'll be in the right place.