How do I ask this girl to hang out or for her number?

Ok, so I'm a Christian, and I love to worship God. I just don't go to church that much, which yes,i'm ashamed of.....But lately I've been oging on wednesdays to my friend's youth group, and I have a blast there......And while I'm there, there's this beautiful girl, about my age (15) and she's obviously a Christian, and we keep sending the signals to each other, especially when we play games in the oyuth group...like,it's ridiculous how much we can tell we like each other...But I've only met her twice,and I dont even know her name.....But I seriously have never felt this way about a girl before.....Usually I just think girls are gorgeous on the outside and I wnat them but I always know I cant ge them...But somehtings different, and no lie, I really ahvent felt this way before about a girl......So this Saturday I'm goign to a park with the same youth group and my friend for this party thing...If shes there,how do i get her alone yet not akward, so i can connect and talk a little more one on one? What kind of pick up lines would be good? How do I ask her for her phone number?How do I ask this girl to hang out or for her number?
you shouldnt have fun at church, it's a place to worship