Question with weight training?!

Question with weight training?

I have a question about my weight training. I am 17 years old, i would say i am not fully developed as of yet, but will get there some time in the near future. I have been doing lightish weights for about 2-3 months. I have noticed that my arms are quite small, compared to my body. It makes me look big, as in like fat. What workout is best for my arms (shoulders, tricep, bicep etc...) that will help make my arm more solid and just bigger.
Thank you all and god bless

then try lifting heavier weights!! lol :)