Well, it is not easy, but not very difficult either. The best is to start with a hello world on each platform, so that you know how it works and fits together. Then google each part as you go a long or ask here. The main thing to learning is having a proper project. Which you have. So it should not take to long.
Notifications on the other hand is a bit trickier. Well, showing a notification is the easy part. But if you want it to be push notifications, then it will get a bit tricky for a beginner. But there are lots of tutorial resources out there on the net.