Unsure of what distro to load on my Mac Os El Capitan(10.11.6)

I am absolutely new to Linux and computers in general. I am currently reading and trying to learn as much as I can about it. I'm currently reading "Linux in easy steps-by Mike McGrath however I don't see any mention of loading Linux on to a Mac. I don't want to screw up my machine by putting something on it that will conflict with the OS. Thanks for your help.