How do I set up SSL?

Hi,

This is an unusual situation, our client is limited by law from receiving revenue generated from online sales. But they can receive credit card information to process on a machine in their office.

Basically, we need a secure way for the customer to give their personal information & credit card to my client.

We have not touched SSL before so we are unexperienced in this area and would like to find out as much as we can. Can you tell me what they/we need, please?

Thank you!
-meaty