Shopify Project add API calls and a payment webhook

I am looking for help with a Shopify project. My goal is to add API calls and a payment webhook. I currently have some API calls but need additional integration that I'm hoping you can provide. As far as payment webhooks go, I'm not sure if I need them so I was hoping you could fill me in on that. I'm looking for a freelancer who is experienced with Shopify projects and can provide the necessary API calls and setup the payment webhook (if needed).

Please write "men" before your proposal to make sure project understanding.