You can render the documentation locally by calling:
make docs
The result is displayed in folder Documentation-GENERATED-temp.
Install the requirements:
make install
Apply automatic coding guideline fixes:
make fix-cgl
If you don't have make installed or wish for finer control, you can run the tests directly:
Build/Scripts/runTests.sh -s h
If you have some general TYPO3 support questions or need help with TYPO3, please see https://typo3.org/help.