The easiest way is to contact your current merchant services provider (credit card processor) and inquire if they offer the service. They may need to upgrade your POS hardware and/or software.
Most merchant services providers also can supple sample code and marketing materials. If integration into your website requires more extensive coding, your development team will want to become Apple Developers, if they aren’t already.
I’ve linked to several Apple Support documents to help with the project.
Payment Platforms - Apple Pay - Apple Developer
Apple Pay | Apple Developer Documentation
Setting up Apple Pay | Apple Developer Documentation