Subpanel

Pretty good articles and video help:

How to Install and Wire a Subpanel by Ask The Electrician

http://ask-the-electrician.com/sub-panel-electrical-wiring.html

How to Wire a Subpanel by klowny1969 https://www.youtube.com/watch?v=suf9F2Hev50

NEC Subpanel Code Inspection Tips by softcellelectrical

https://www.youtube.com/watch?v=0rV1f0egkFk

How to Install a Subpanel by askmediy

https://www.youtube.com/watch?v=bDuOVe19C8M

DIY Electrical Wiring Workshop Electrical Panel by scottpdotnet

https://www.youtube.com/watch?v=zNUr6y-i-u8