Update 33. 3:33pm. I realized that I lost the .htaccess file in my main folder. I learned previously that .htaccess files simply put instructs servers to behave a certain way.
In this case, I wanted to hide .html in the URL path. To do this, create a file named ".htaccess" and save it on your root directory. Within the file, copy and paste the code below.
Here is the prompt and the corresponding result.
create .htaccess so I can add .html in my URL paths
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)\.html$ /$1 [L,R=301]
RewriteRule ^([^/]+)/?$ $1.html [L]