Yes you can. You will require a dedicated IP address to install SSL Certificate for your website. Generate Certificate Signing Request (CSR) from WHM >> SSL/TLS >> Generate a SSL Certificate and Signing Request by filling in the required details. It will generate the CSR, key and a self signed certificate for the domain. Once done you can purchase the certificate from Certificate Authority (CA). After it, you can install the certificate on website at WHM >> SSL/TLS >> Install a SSL Certificate and Setup the Domain.