@Keshav_Sharma there isn’t a documentation on the source code, as far as I’m aware.
Regarding contribution, you can take a look here: https://github.com/bjorn/tiled/blob/master/CONTRIBUTING.md
You can find the source code in the
src folder where the code has been divided into multiple folders. For most of the features you can start by playing around with code in
src/libtiled (the Tiled library which contains various definitions and methods for
Map, etc. which power the whole source code of Tiled) and
src/tiled (the main source code of the Tiled application).
You can take a look into existing pull requests which implement simple features to get an idea of codebase and how you can get started with it.
Regarding documentation, I think it will be a nice idea to write a small guide for new contributors. What do you think @bjorn?