What is the best guide for the NEX 5N?
The best guide is...
The Complete Guide to Sony's Alpha NEX 3, C3, 5, and 5N Mirrorless Cameras by Gary Friedman
This will run you about $22 for the eBook. I know you said you were a student, but (as a person that has been studying photography for 30 years), you won't be sorry you spent this money (skip 1-2 nights of pizza and beer and you'll have it covered for sure). You'll learn more in 3 days reading this book than you will 3 years of Google and YouTube searches. Even as a student, your time has to have some value to you. You won't be sorry, unless you aren't truly serious about learning the 5N.