If you are using WordPress, I would suggest to find a contact form plugin for WordPress (like Contact Form 7) and an SMTP sending plugin (like WP Mail SMTP). That’s a much easier route than trying to implement it with a completely standalone script.
The config.example.php can be found in the base folder of the zip file. It should be in the location where you uploaded the contact form code.
You can copy and paste files from the file manager through the right click menus.