badge question

PureDisaster

I'm hoping for a BFP this month which would make my EDD around my DH's birthday (he is SUPER excited about that). So while I am waiting to POAS I decided I would take a shot at the May badge. Since I am pretty new here, I'm not really sure how the whole badge thing works. My question is, are there any rules to making a badge (like using a copyrighted image and tweaking it or such)?