If you want to do this yourself then you need to purchase a
SSL certificate. I have had no experience with this myself, but someone will be able to help I'm sure.
There are plenty of thrid parties out there that can take the details and pricess it for you, two of the biggest being worldpay and paypal, but there are plenty to choose from.
It will all depend on what you are looking to do to what software you end up using. If you can give a bit more detail about the end goal / objective then we will be able to help more.