to use https you have to purchase a secure certificate from verisign and then get it installed by your provider, you can (and should) probably just purchase it through your provider.
Once that is done you just access the site with https instead of http and you're using https there is no difference from a programming perspective since the programming is on the application layer and the https is on the transport layer.
Now, the disadvantage is speed. https sites are slightly slower to load because of the encryption that goes on with https.
