As mentioned in [our guide]  about how to create a SSL certificate, once you generate the
cert.csr file, you have to send it to the Certificate Authority so they can do all the check that they need to do (and probably gotten payment from you), they will hand over your new certificate to you. Then, you will need to upload the signed certificate to your server and configure Apache Server to use it.
But apart from that and according to a previous message
Ok, so I got a GoDaddy Class 2 Certification Authority Root Certificate file and I have no idea what to do with it.
I understand that you already have a signed certificate so you only need to install it. Could you please tell me if I am wrong?. If you already have a signed certificate, you will need to upload the signed certificate that GoDaddy sent you to your server and configure Apache Server to use it. You can find more information about how to upload files to your server using SFTP in our guide at https://docs.bitnami.com/google/faq/#HowtouploadfilestotheserverwithSFTP?
Hope it helps,