Free SSL Certificate for IIS.
Download latest from:
letsencrypt-win-simple – https://github.com/Lone-Coder/letsencrypt-win-simple/releases
Create both port 80 and 443 bindings to a Site in IIS and set a hostname.
Port 80 needs to be publically available for a certificate to be issued (and renewed).
Create a self signed certificate for now.
It will detect your IIS binding and issue a certificate. It will create a scheduled task to renew the certificate at 60 days.