Every Podpage website comes with SSL — the security protocol that encrypts the connection between your visitors' browsers and your site (that's the padlock in the address bar). When you connect a custom domain, we issue a free SSL certificate for it automatically.
There's nothing for you to set up. As soon as your domain's DNS is pointed at Podpage, we start issuing the certificate. During setup you might briefly see a security error when visiting your site — that's normal, and it usually resolves itself within an hour or so.
Tip: Haven't connected your domain yet? See how to connect your domain name to your Podpage.