you can start by going through the project Idea, here is the list
Chromium GSOC'22 project list. In this, you will find all the projects details, the tech stack required, and a proposal template. To get started, you can start contributing by starter bugs and exploring the codebase.
Each Repo also has
contributing.md file which will guide you on how to get started with a contribution to that repository. Explore the codebase and check if you can make some starting contributions. You can visit this
thread on a few resources and steps on contributing to Chromium.