well i think they meant to put a label on it. you could do a search in Yahoo for signed quilt labels and click on Images, then on search. you can see examples. I forget to put labels on mine though. it's a good practice to do, so get with it.
you could do one with embroidery or use Micron Pigma pens size .05 to sign (just heat set with iron). there are colored pens and such out there to use too if you want to do more coloring.