Congratulations on booking your first cruise! I know you'll love it.
However, beware of drink prices, they are high, and with the added gratuities you may find that your bar bill outnumbers the price of your cruise.
I don't order beer, so I can't tell you how much they are, but cocktails and mixed drinks are $6.95 on Carnival, at least they were last November, probably gone up again since then.
I do know you can get a deal on beer by ordering by the bucket (not sure of the price) but it does save a little.
Enjoy your cruise!