I have about 30 classes resides in 7 packages in my android application: 

[![enter image description here](https://i.stack.imgur.com/MZUC8.png)](https://i.stack.imgur.com/MZUC8.png)

I want to make a class diagram and CRC ( class responsibility collaboration) cards for it. But I get confused because the class diagram will be a large and complicated diagram. According to this [Answer](https://stackoverflow.com/questions/31975109/android-class-diagram-uml) form a previous question. I had to make a class diagram for the main classes like Fragment and services etc.

If anyone can give me advice about that. Also, I need to implement the layers of architecture ( Presentation layer, business layer , and data access layer ) according this: 

[![enter image description here](https://i.stack.imgur.com/1Dje2.png)](https://i.stack.imgur.com/1Dje2.png)

But I don't know where to start since i am using a php service. Any tips ?