Hi Carlos,
How wonderful to be bringing your daughter to Walt Disney World for her first birthday! What a magical way to celebrate.
Spending a day at Magic Kingdom will be so much fun for your little one. Be sure to ride "it's a small world" and watch her eyes light up at all of the dancing, singing dolls. Magic Kingdom has so many attractions that you might want to consider spending a second day there if you feel like you have not seen everything you wanted to see on that first day. If you want to go to a second theme park, you might consider Disney's Hollywood Studios, which has characters from Disney Junior at Disney Junior - Live on Stage! and other great shows that your daughter might enjoy such as Beauty and the Beast - Live on Stage. Another option, if she is enamored with animals, is to head on over to Disney's Animal Kingdom, where she could see live exotic animals on Kilimanjaro Safaris and many other attractions.
As to special treats for birthdays, be sure to pick up a "Happy Birthday" button, free of charge, for her at Guest Relations at any theme park. Sometimes guests wearing this button get a little extra pixie dust sprinkled on their day, like a cupcake at the end of a meal. Extra treats are not guaranteed; however, it is also just fun to hear cast members and other guests wishing your little one a happy birthday! For a charge, you can also order your little one a birthday present from
Disney Floral and Gifts, who can customize a gift just for your little one. After you have looked at their website, I suggest that you call them at 407-WDW-GIFT (407-939-4438) to speak with a Dream Maker who can help you with your order.
I hope that these thoughts are helpful for you, Carlos! Have a wonderful time planning your trip, and please do not hesitate to ask if you have any further questions.