Help me secure my recreational website.

I have this website on Digital Ocean and I am using webmin to administer. I think I want to put in a self signed certificate (this is for recreation, not commercial purposes and I don't want to pay) and leverage port 443 instead of 80 because I have users authenticate. BTW, if there is a better way to encrypt the transmission without paying for a certificate, I'm all ears. Your job is to help me figure this out and help me configure this properly.