so boys i need help what should i do

So first i have 21 and , im in university all days i take train and I have a crush on a girl who takes the same train than me . I just want ask Instagram @ , but I lose all confidence. What should I do? I just want to wake up one day and have the courage to go talk to her. This sounds weird but in my last long term relationships they were the ones who talked to me first so I never step out of my comfort zone, I only made the first move if I was drunk at night, just a late night low. btw i dont hsve tho muchs crush probably my last with 16-17 Y. Im accepting any advice