I'm too scared to ask her out!

I'm 15 years old. There's this girl that I've been talking to via text, facebook and snapchat. We've been talking since around January, we talk quite a lot, she is really sweet. We get along really well and I think she likes me but I don't want to ask her out over the internet. The prom is coming up and I've never met her in person, how should I approach this situation? She even puts an extra 'x' sometimes! I know this is realistic affection towards me but am not sure if she wants to go out with me. How do I remain confident at the prom? How would I keep the conversation going? What shall I say? How would I flirt? How would I ask her out? Is there any signs that she likes me in person? I'm really shy and can be really awkward and things like small talk with girls I would find really difficult so please please help, just some advice so I don't mess this bid opportunity up!

I would suggest you meet her in person BEFORE you ask her to the prom. Say something like "I really like what I see of you online and I'd like to get to know you better. Could I meet you in person sometime soon?" If she says "yes", then go right in and figure out a time and place which suits you both. Don't leave the 'yes' hanging to be acted on at a future date because you may lose courage to go back in.

If you start hanging out with her and seem to have a rapport, then it's time to ask her to the prom.

I wanted to see her at the prom but not go together and I'm not sure how to act or what to say? If we met up what would we do where would we go? I don't want to mess it up.

Maybe somewhere attractive in your area or cinema.