Don't worry about being shy with girls, just treat them as equals, be friends with them and anything that develops in a relationship will be more natural. Above all, never pick a fight with a girl as they don't fight fair
All the best relationships (including my current one - I've been with the wife for 12 years now) have been when I haven't been looking for a relationship - it's just happened.
Enjoy being young and learning - lots of time for messing about with bumpy bits later on in life and you'll love beer in a few years