After receiving the SSL certificate, install your server as an intermediate certificate that establishes the credibility of your SSL Certificate, binding it to the CA root certificate. The instructions on how to install and test your certificate will be different, depending on your server. The most important part of an SSL certificate is that it is digitally signed by a trusted CA, such as DigiCert. Anyone can create a certificate, but browsers only trust certificates that come from an organization that is on its trusted CA list.
Browsers have a pre-installed list of trusted CAs, known as the trusted root CA store.
An SSL Certificate issued by a certificate authority for an organization and its domain/website will verify whether a trusted third party has authenticated the identity of that organization. Since the browser trusts CA, it now trusts the identity of that organization as well.