I just CAN'T vibrato

I'm 16 (f) soprano and I feel like I have a relatively ok voice. I've always wanted to try operatic singing b/c my voice can reach C#7 but for some reason I just can't vibrato. People say it's because of tension but I don't feel any tension whatsoever. Can anyone tell me what I could do to get my vibrato? 😭😭😔