How to install a certificate on CloudFlare?

Question

cloudflare

Hello!
I use hosting: beget I
take protection from CloudFlare on the tariff: Pro 20$
And I bought a comodo certificate separately
I don’t understand how to connect it all ...
on cloudflare I turn on SSL:Full mode

Next, I try to add my certificate I insert my certificate

code in this field:
- ----BEGIN CERTIFICATE-----
code from the site_ru.crt file
-----END CERTIFICATE-----
And I get the error
private key or certificate is not valid CSR
I also tried to insert the private key, and certificate, and all the same = the same error pops up.
How to add your certificate to cloudflare correctly?...
------------
I read in their documentation that you can download only on the $200 and $5000 plan.
How to be then?
Put your purchased certificate on beget bind, and what settings should I specify on cloudflare?
--------------- When creating a free
Origin certificate from cloudflare - it gives a public key, a certificate - and writes that you need to put it on the hosting, enter ... And then how will my certificate work?