SSL has nothing to do with your code. The only time your could would effect SSL is it you were to hard code images from a URL that did not have SSL and then your users would see the message that not all parts of this page are secure yada, yada... Mark
There is code involved. The code is making sure that you redirect users to the https instead of the http when needing to use the SSL. Just remember that session variables won't carry over from the http to the https site if you are doing some kind of a shopping cart with session cookies. I recently just had my first experience with SSL. At first I went through StopMommy's cheap SSL. It turned out to be a disaster. At first we kept getting an alert saying that the SSL wasn't for our domain. Then we moved hosting companies. The second hosting company wouldn't even accept the StopMommy SSL. I ended up purchasing one through another company and had to pay a little bit more for it, but in the end it was a much smoother process and I'm not getting any errors now.
aGig is correct in that there is strictly no code change necessary however you may want to do a redirect to ensure that the user is using the secure version of the page.
JOhn, what exactly are you trying to do with the SSL cert? Just run one on your server and ensure users use it? POST to another server over HTTPS? Install an SSL server on your box?