How to register with CloudFlare

I just started installing Cloudflare but it shows that the domain is sub domain.

I can tell this is not error and it’s pretty self-explanatory, you can’t use SSL or cloudflare on provided by hosting subdomains.

Yes, is indeed a subdomain. And given that Cloudflare shows it as an error message, it’s easy to tell that Cloudflare does not support using subdomains. That’s a restriction on Cloudflare’s end, I don’t think anybody here can “fix” that.