ANDROID- Send money to user? Paypal

In my Android app, I need it to where, if the user has enough points, then they can click a button that will then send them money through PayPal. It's basically like those apps where you watch ads for points, then you redeem for PayPal cash. The problem is, I can't seem to find a way to do this, even though I've seen it done with countless apps.

To give a better understanding of what I am trying to achieve, here is a scenario:

Bob has 1,000 points. In the app, 1,000 points is $1 USD. He clicks a button that says 'Redeem $1'. The app then prompts him to sign into his PayPal account, and then it sends Bob the money (to his PayPal).

How can I achieve this?