Free lance for my software website

Hello id like to get pay pal working on my website that’s almost completed. I will be charging a monthly fee. How do i go about doing this? how will my clients be able to get the software when they order. Would like to hire someone for help

You could do that by using a 3rd party service such as Fast Spring

Just link the buy button to the fastspring site and the rest of the process should be done within their site/system.