For contributing to the website e.g. writing a Tutorial, please see https://vrchatapi.github.io/tutorials/contribue-website/.
For contributing to the OpenAPI specification (which produces the API Docs and the language SDKs), please see https://vrchatapi.github.io/tutorials/contribue-api/
For any questions at all - we are more than glad to help with getting started to contribute - please join and contact in the Discord Community.