Here first you have to understand how Appmaker works. Then start play with it's each brick. Then you have to write each brick documentation.

Each brick documentation consist --

1. What is the Brick name?

2. How it works? (Include some screenshot of how it's signal works)

3. Document properties of this brick

4. Possible purpose where we can use this brick.

5. (If possible screen cast of this brick)  

Links : https://apps.webmaker.org/designer