How can I rekeying?

this answer from my housting Support : The procedure of the rekeying the SSL will be done by cloudfare. Once done and SSL is again active on the website, it will work fine.
I don`t know how I will rekeing? can you help me ?

Maybe they mean renewing your site’s TLS/SSL certificate. What’s the domain?

no My ssl is new

That domain is not using Cloudflare DNS or Cloudflare’s proxy service. It has a self-signed certificate.

If you do add it to Cloudflare, you will need to use Full (not strict) mode. It’s not the best way to do it, but it will work. A better self-signed certificate would be an Origin CA certificate from Cloudflare and will let you use Full (Strict) SSL mode.