The second half will be a lot faster than the first part
Click on the Download Button
Choose your server from the drop down menu. Apache is the most common.
Now, Download the zip folder. Unzip it and You are going to want to upload the first document out of the 3 that are there.
Upload it by going back to the cPanel>SSL/TLS>Certificates (CRT)
Next Browse your computer and find the file from the unzipped folder that ends with .crt (its the first one on the list)
Then just upload the certificate
Last and final Step