I'm trying to install Macos 11 big sur.

Hello everyone, I have a Macbook Pro 2012 model. It had macos 10 catalina installed in it. I just received this computer and I have never used a Mac before. I walked around in it for a while, but it was very old. Even the simplest spotify wouldn't let me install it. So I decided to upgrade. I talked to a friend. It told me to install ubuntu. He said it would get better. Technically my friend was right, but the computer started to overheat. I am not satisfied with this situation and I am thinking of making macos 11. I need to burn the macos 11 big sur file I found on the internet to USB and install it from the bios screen, right? Can someone with knowledge on this matter help me?