How to edit nginx.conf to increase file size upload

I want to increase the `maximum file size` that can be uploaded. After doing some research online, I found that you have to edit the file 'nginx.conf'. The only way I can currently access this file is by going through Putty and typing in the command: vi /etc/nginx/nginx.conf This will open the file but I have 2 questions now: 1. How do I edit this file? 2. I found online that you have to add the following line of code: `client_max_body_size 8M;` Where would I put this line of code in `nginx.conf`?