Uh, currently reading books on eaglecad to bone up for a project. Def recommend the book by Simon Monk (https://www.amazon.com/Make-Your-Own-PCBs-EAGLE/dp/0071819258/ref=pd_sbs_14_t_0/161-9832054-0955403?_encoding=UTF8&psc=1&refRID=HFX9165081XSERVFMVPH) if you want to start making your own circuits.
Also Luke Cage. One of the better 'flix originals I've seen this year (along with Stranger Things) for sure.
You may consider a hobbyists book to start with, something like this Eagle Book or this user But for the real details I recommend this book or similar
Besides knowing the tools you really only need to know Tx Line analysis and (Signal/Power) Integrity information. Which may be some of the most important details to PCB design in my very limited opinion.
I'd recommend this book:https://www.amazon.com/Make-Your-Own-PCBs-EAGLE/dp/0071819258
It'll walk you through how to make your own PCBs for very low cost. You could also look into joining a maker/hackerspace. Many of them have relatively cheap monthly memberships and everything you need to make your own boards. Here's an example of a good one in chicago: https://pumpingstationone.org/
No your the shit! This is the best thing that came out of humanity able to create your own PCB from scratch there's tons of books on Amazon: http://www.amazon.com/Make-Your-Own-PCBs-EAGLE/dp/0071819258/ref=sr_1_1?s=books&ie=UTF8&qid=1423174971&sr=1-1&keywords=PCB
and places to order to make a custom PCBs: http://www.custompcb.com/
There are people into building custom PCBs just take a look at Raspberry Pi you can even make your own computer or device or whatever. Think about the possibilities to the /r/PCMASTERRACE!
EDIT: Sorry I forgot it wasn't a threat
EDIT: I just fucking found this: https://www.youtube.com/watch?v=N3DGbwVXyN8 I'm fucking subscribing