<human>: Could you distill the essence of the text into 1-3 sentences?

I'm 17 nearly 18 male, and she's 17 female, 18 next year

Length of relationship... 0

Backstory: I have never had a girlfriend before. I've only ever liked two people, one for 5 years and the current person... 
The girl I currently like I have done so for about 1-1.5 years. Let's call her Maddy. To my knowledge Maddy has never had a boyfriend, we are good friends and talk to each other a fair bit. 
I don't really see her outside of school (yr12 in Australia) for two reasons, I'm not very sociable and she lives out of town, about 15 minutes drive.

My problem: I am a naturally shy person, I've been a physically small person my whole life up until recently, I could now probably be considered short to average.
 This has resulted in me never taking initiative with people and I don't know how to ask someone out. A close group of friends (all of whom have reddit, hence the throwaway) have recently found out about me liking Maddy and are trying to get me to ask her out, to ensure I do this they have said that if I don't by Friday then they will tell her, so they are basically giving me a reason to act out my feelings. 
However, I don't know how, I don't know what I should say or how to say it (keep in mind she has also never had a boyfriend so there is a high possibility of awkward times), or how to be a boyfriend in any way.
<bot>: I'm a shy guy who needs help asking a girl out for the first time and how to follow through being a boyfriend