The project uses Leiningen 2 and requires a recent MongoDB to be running locally. Make sure you have those two installed and then run tests against all supported Clojure versions using
./bin/ci/before_script.sh
lein all do clean, javac, test
Then create a branch and make your changes on it. Once you are done with your changes and all tests pass, write a good, detailed commit message submit a pull request on GitHub.