Hi Nelly! Don't worry...if you want to find characters in the parks, there will be Time Guides and Park Maps available at each of the park entrances. The Time Guides will include character greeting locations and times.
However, when it comes to meeting characters, I like to have them come to me whenever possible! And by that, I mean booking a character meal. A few you may want to consider:
Akershus Royal Banquet Hall located in the Norway Pavilion at Epcot. Here you can have breakfast and may meet Ariel, Belle, Jasmine, Snow White, Sleeping Beauty and Mary Poppins.
Cinderella's Royal Table located in the castle at Magic Kingdom. For breakfast, you may meet Cinderella, Fairy Godmother, Belle, Jasmine and Snow White.
1900 Park Fare located in the Grand Floridian. For dinner, you may meet Cinderella, Prince Charming, Fairy Godmother, Lady Tremaine, Anastasia and Drizella.
These dining locations are very popular so you'll want to make reservations 90 days before you check into your resort if you are interested. And as always, characters are subject to change.
I hope this helps and I hope your vacation is truly magical! Diane :)