How can I find my passagio?
 

I mean I know what passagio is (a passage from lower to higher register), but how can I find it in my voice???

Sing from a very low note to a very high note all in one breath. (Kind of like a siren sound). Some people move freely from their chest voice to their head voice (moving over the passagio without a 'break' in the voice) while others kinda 'jump' from their chest voice to head voice. When you sing from a very low note up to a very high note in one breath, when you can feel your voice moving out of your chest and into your head, this is the passagio.