How to use Cloudflare SSL Origin Certificates with Nginx

As Per this article

Then you will have to merge your origin certificate and the Cloudflare Root CA in a single file :

cat yourdomain-origin.pem cloudflare_origin_rsa.pem > yourdomain-crt.pem

after doing this i dont know what output should i get when i run it simply show me no such directory

can someone tell me what mistakes im doing