Well, there's a tehnique used by Mariah Carey especially, when you're singing very high, make it sound special, a "head" voice. i don't know if this is the best name to say. for example, in her song named Emotions, when she says "Inside" (I don't know if it's real, but i'd like the way it feels inside) - or in All I want For Christmas is You - at the last chorus... (All i want for Christmas iiiis... you) anybody here knows how to make this/ how to place the sounds that are coming out?!
also, any sites/information/lessons about voice performance - is good and it will help me for sure