Atmega 16A bootloader

Hi Guys wish you are having happy holidays,
I’m trying to run an Arduino code on an Atmega16A and I needed the bootloader for it. I found on Instructables a detailed description of doing that but it doesn’t work and always shows an error while burning the bootloader. I have to mention that my knowledge about programming is really very few and I barely understand what’s done in the bootloader. So could anyone help me understand how I could do it by myself and make it work?