Apart from reading, and trying to understand the architecture, these are some things you can do: 1. Fix a couple of bugs 2. Add a small feature 3. Refactor a

Apart from reading, and trying to understand the architecture, these are some things you can do: 1. Fix a couple of bugs 2. Add a small feature 3. Refactor a small piece of it Always start with few small things and keep increasing the complexity of the things you do. Working on a codebase is the best way to understand it.