Hi & welcome. Do you have any specific job openings in mind, or just for fun (like me)?
Can you be more specific about which aspects of Linux coding?
Start with syscalls (man -s 2). kernel.org? GUI? Any particular applications?
What specific web-searches have you tried? Do any particular books (Amazon) interest you?
Tell us a tiny bit about your Linux experience, PC resources, ... Best wishes; ENJOY!
p.s. Here's one (old but free) as a start:
http://advancedlinuxprogramming.com