Where to put .htaccess file to do a redirect

I need to redirect my website to a non www. URL by using an .htaccess file.

Please say where to put .htaccess file to do a redirect or suggest any other ways this could be done. I tried /usr/local/nukona and /usr/local/nukona/www - its a CentOS on-prem server.

I tested to see if it is using the .htaccess file by putting junk/erroneous data in it and seeing if it errors.

The reason is that we only have certificates for the non www. URL so users go to the www. URL get a SSL warning.

Many thanks

John