The first thing you need to realise, is that you
don't have to tell your parents; not yet, at least. I'm 16 and I
still have yet to tell my own parents and family about my orientation.
I mean, of course you may need to tell them one day, but only when you
want to.
There are lots of ways in which you could tell them, but you should always do what
you feel is right. Someone I know simply walked into the room, and told his parents
he had a boyfriend. Another person I used to know just asked if they could go to a LGBT (Lesbian, Gay, Bisexual, Transgender) meeting by sending his parents a link by email.
Just do
what feels right,
when it feels right.
In my belief, you will not go to hell for being bisexual (or gay etc). Many people have many different views, but I believe that as long as you're generally a good, kind person, being bisexual or gay or whatever isn't going to make you go to hell / stop you going to heaven

And hey, don't sweat it. I've been thinking I'm gay for around 3 years now, and I still accept the fact that it's possible I could "change." But do I want to change? Do I care if I do? Nope.