Congrats on graduating, and even more congrats on securing a job as an ICU nurse as a new grad!!!!!
Your feelings of knowing "so little", yet being "eager to learn everything" are perfectly correct. You're miles ahead of the folks who assume that they already know it all, and will wow/impress their fellow ICU nurses with their schoolwork-based knowledge.
You might want to check out icufaqs.org, and I HIGHLY RECOMMEND their book available at Notes on ICU Nursing: FAQ Files from the MICU: Second Edition by Mark Hammerschmidt (Author) .
Another good resource (deeper, more technical details) would be Paul Marino's "The ICU Book", available at:
The ICU Book, 3rd Edition: Paul L. Marino, Kenneth M. Sutin: 9780781748025: Amazon.com: Books
...although I dread paying $65 or so for a used paperback....
Congrats, good luck, and all that jazz!