How to renew ssl certificate on Ubuntu, Nginx?

Question

Nginx

How to update the current certificate for a domain?
In the settings for the nginx domain, the ssl storage parameters are now registered:
ssl_certificate {path}/chain.crt;
ssl_certificate_key {path}/private.key;
The provider sent the following files:
An .rtf document in which:
Your certificate is provided below
-----BEGIN CERTIFICATE-----
...
Root certificate
-----BEGIN CERTIFICATE-----
...
Intermediate certificate
- ----BEGIN CERTIFICATE-----
...
Certificate request
-----BEGIN NEW CERTIFICATE REQUEST-----
...
{domain}.csr file:
-----BEGIN CERTIFICATE REQUEST -----
...
File {domain}.key:
-----BEGIN RSA PRIVATE KEY-----
...

Answer 1

-----BEGIN CERTIFICATE-----
...
-----BEGIN CERTIFICATE-----
...
-----BEGIN CERTIFICATE-----
...

this part (with all three certificates in one file) in {path}/chain.crt

-----BEGIN RSA PRIVATE KEY-----
...

and this one in {path}/private.key
Ps: the fact that the private key is sent by the provider (and not generated on your side) makes this certificate a complete fiction