Secure Pages

I apologize for what turned out to be too vague a question.
The security I am referring to is exmplified by the little
key icon in Netscape.  By a secure page, I am referring to
the data, such as credit card numbers, being encrypted when
delivered via a form.

The security is also exemplified by the Netscape for message:

Any information you submit is insecure and could be observed by a third party while in transit. If you are submitting passwords, credit card numbers, or other information you would like to keep private, it would be safer for you to cancel the submission.

Thanks and sorry again.

I have been asked to set up a secure Web page.  My ISP says they will do this for me at a cost.  My question, is it possible for me to setup the secure Web page myself through HTML, CGI, etc.?  If so, how do I accomplish this, and what do I need to know from my ISP?  Sample code, etc.  would be extremely helpful.

Thanks Brett