First, it isn't Dora, it's 'Go Diego Go!'. Be sure you(you doesn't refer to an individual) get that straight or else you'll just confuse people.
Nickelodeon keeps their email addresses pretty secure. The only way you could email them is to 'email' Nick Online, (nick.com has a Contact link at the bottom of the page) but that's not really contacting Nickelodeon (you should contact Nickelodeon Studios) and you probably won't get a reply. Your best options are to write by mail or call by phone. Only actually calling them will ensure a response.