Follow this web page to get a key and csr file.https://help.ubuntu.com/lts/serverguide/certificates-and-security.html
I did this for both pie-lter.ecosytems.mbl.edu and arc-lter.ecosystems.mbl.edu sites
Note you need to put in the full site name when genrating the .csr file.
I then submitted the csr file (2048 bit long modulus) to mbl helpdesk to get a certificate.
Copied the certificates to /etc/ssl/certs and key file to /etc/ssl/private
added a redirect in apache See https://www.drupal.org/https-information
These pages were also helpful:
To see the server and time for the certificate use:
openssl x509 -noout -in arc-lter_ecosystems_mbl_edu_cert.cer -subject -issuer -dates