There are many ways to contribute such as logging issues, submitting pull requests, and creating suggestions.

After cloning and building the repository, check out the issues list. Issues labeled good-first-issue are great candidates to pick up if you are in the code for the first time.

If you want to understand how .NET for Android works or want to debug an issue, you'll want to get the source, build it, and run the tooling locally.

See the documentation on "Building from Source" in https://github.com/dotnet/android/blob/main/Documentation/README.md#building-from-source