How a MacBook Pro boot on something? (detailed answer needed)

Is someone can explain me how my macbook pro boot on a device ?

I'm trying to set up windows but it's $@$*!& (please, don't tell me use bootcamp or do this, i'm trying since 2 weeks without results).

i can see the manual refind install to help, but no "bless" o "make boot" worked on my win7 iso's.

i guess there is some things like :

-->The mac can read if there is a folder named "EFI" or "BOOT", without that it will think it's not bootable

-->It will then read the .efi file, who give (maybe) the correspondance config file to how to use screen, keyboard etc.. and maybe some drivers (that is made by bootcamp, but even if i can found a bootcamp image, i'll have to manage the efi & config files to adapt them to my mac and the system i want to run).

-->maybe it will check if the files are "authorized" to be used as boot, thinking of "bless" command who should have some applications.

Understand this system would help me a lot for restore / copy / install etc..

I understand that there is several boot system, efi, and others windows one, and several efi version, and bios emulation system. for now i want to focus outside the bios emulation world. (win 7 and linux can run without this). grub on mac ?

I'm ready to learn !