After reading the "benefits" that I could have after changing the kernel of my phone I would change the actual one that my phone has. I've already flashed custom roms in the past and my question is if the procedure to change kernel is more less the same , so do I have just to flash it ?
Yes the procedure is pretty much the same. Infact some custom roms already has the custom kernel inside them. Anyways if you want to flash a custom kernel, find one for your phone ( probably from xda-developers ).
If you found a kernel, if its already in a flashable zip, just flash it via recovery.
Otherwise, put your phone in fastboot mode using button combination or via ADB by typing
adb reboot bootloader and flash the kernel using this command
fastboot flash boot filename
Note you need to have an unlocked bootloader for this to work and