a version control system. You can clone a .git to your machine to make changes.
eg. git clone https://git.hyperbola.info:50100/services/hyperbot.git
Pull new commits -> git pull
If you have plans to propose new changes, just create your commit with your modification, eg. git add your_modified_file.txt
git commit -m "Add new change, blah, blah"
Generate a patch of your commit -> git format-patch -1 and send it to us via issues.hyperbola.info, forums or mailing lists as pull request. So, we will add it as -> git am your_generated_patch