I use the same tools you do for managing certificates. What you created is known as a “self-signed” certificate, which won’t do anything for you. As far as getting a certificate signed by Let’s Encrypt, you have options. I’m guessing you probably generated either a 2,048 bit or 4,096 bit private key using the link under Private Keys. You can next generate a Certificate Signing Request and select that key you generated. It will offer to generate a new key for you, but that key will be weaker (2048 bits) than the one you probably (and should have) generated previously with 4096 bits. From here, you have options.
Recommended by this community: download and configure an ACME Let’s Encrypt client (eg certbot or acme.sh) and run it in “manual mode” to get your certificate. You’ll need to utilize the DNS Editor you mentioned before to add one or more DNS TXT records to prove your ownership. There is also a file-based route too. Many of the other people in this community are more than happy to help you with doing all this.
One-off certificate: You can get a certificate using my website by pasting your Certificate Signing Request in the box then follow the instructions for adding the DNS TXT records just as mentioned above. This is just a web-based ACME client.
Either way you’ll get a certificate so you can follow the link under Certificates (CRT) then paste the certificate in the box and save it. You usually don’t need the CA Bundle as it’s autofilled for you. Be sure to actually INSTALL your certificate from the manager after you save it. I’ve forgotten to do that a couple of times.
Before your certificate expires again, you’ll need to decide if you want to:
- Try to find a client you can install that will automate your renewal.
- Repeat the process you just did to get a new certificate.