How to replace Caddy SSL with COMODO SSL/any of my own certificate

Hi Sir,

Sorry for troubling you many times with frequent questions because I’m really very new to Caddy. Could you please let me know the exact syntax to be mentioned in Caddyfile to replace Caddy SSL with COMODO SSL?

I tried this way in my Caddyfile, but it’s not working

mydomain.com   {
reverse_proxy 127.0.0.1:5000
  tls {
   ca_cert_file /etc/ssl/xyz.crt
   ca_key_file /etc/ssl/xyz.key
  }
}

Below are the files and paths of COMODO SSL on my server;

/etc/ssl/xyz.crt

/etc/ssl/sxy.key

/etc/ssl/xyz.ca-bundle

Please guide me with exact syntax to put in Caddyfile. Thank you in advance!