Learn how to design a PCB for the Raspberry Pi with KiCad in 20 minutes from Chris Gammell of Contextual Electronics:
Shine On You Crazy KiCad
"This course shows how to make a custom but very simple piece of electronics for the Raspberry Pi platform. The primary purpose is to get users building something in KiCad as fast as possible."
This free course contains four videos:
Designing a PCB in KiCad in 20 minutes
Assembling a simple circuit board with SMD components
Writing code, blinking an LED with a Raspberry Pi