How to setup?

I bought Comodo PositiveSSL today, cloudflare SSL/TLS setting is Full, I opened Proxy as Orange cloud , the webpage of website can’t be open, ERR_SSL_VERSION_OR_CIPHER_MISMATCH.
have any solution? Or is there any keyword to find anything that can teach me?

That Comodo cert has to be installed at your server. Hopefully it is.

Then it’s a matter of making sure you have SSL/TLS properly set up at Cloudflare.