Implementing "Donate" functionality

I have created a free Android app, and i want to im开发者_开发知识库plement "donate" functionality, but have no idea how to do it? Can someone help me with that? Some tutorial or something like that? How to implement it for countries not supported bu PayPal?

There's a tutorial on implementing PayPal with your Android app here. Check this post out for why it's difficult to implement in-app billing for an Android app.

You may try to implement In-App Billing, it seems like the simplest way to me. Here's the link: In-App Billing

Hope this helps.