While Crucial can usually provide you with an SSL certificate for much less expense & include automated installation due to our partner relationships with a variety of SSL providers, if you plan on purchasing an SSL certificate from a third-party, here is a summarized version of the steps you need to take (detailed instructions can be found after this):

1. Generate a CSR and Private RSA Key from cPanel
2. Order the SSL certificate using the previously generated CSR
3. Follow the SSL provider's instructions to authorize the SSL certificate order
4. Once you receive the certificate key, install the certificate from cPanel

Click here for detailed instuctions for purchasing and installing an SSL Certificate.