The MCTS consists of test packages for various areas. If you are interested in developing test cases to an existing test package, you should first contact the maintainer of the test package. The maintainer for a test package is responsible for incorporating the test cases to the package and ensure that your test cases meet the quality criteria. The maintainer instructs you how, in practice, your test cases are brought to the clone of the MCTS she/he manages. At the end, the maintainer will submit the merge request containing your test cases to the MCTS maintainer who creates the MCTS release. The current maintainers are indicated in the content description tables in MCTS main page.
If you are interested in creating a whole new test package, you should directly contact MCTS maintainer Jeff Zheng to request your package is to be included to MCTS release. With such a request, you need to nominate a maintainer for the test package, who is responsible to ensure that the quality criteria is met. The maintainer needs to create a clone of the MCTS master repository where changes are to be committed and create merge requests towards MCTS release. In addition, the nominated maintainer must create a process where test cases can be incorporated to the package from other developers. The merge requests and release process is described in MCTS Release Process page and the existing releases and future plans is described in MCTS Releases page.