I am looking to have users on my website submit their bitcoin id and be able to accept bitcoin from other bitcoin user as donations.

I am brand new to this. I'm using PHP.

So basically this is what I want to happen.

User A signs up on my website and gets a profile

User A enters their bitcoin address that they want to accept payments to

User B goes to User A's profile and selects to send bitcoin to them

My backend PHP code facilitates the payment from User B to User A and gets notified of a successful transaction.

From what I'm reading there are multiple places someone can have a wallet. Is there a centralized way to send to and from any wallet?