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CONTRIBUTING.md

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+# How to contribute
+
+
+
+## Getting Started
+
+* Make sure you have a [GitHub account](https://github.com/signup/free)
+* Fork the repository on GitHub
+* Install clang-format (download from [here](http://llvm.org/builds/) for Windows)
+
+## Making Changes
+
+* Create a topic branch from where you want to base your work.
+  * This is usually the master branch.
+  * Only target other branches if you are certain your fix must be on that
+    branch.
+  * To quickly create a topic branch based on master; `git branch
+    my_topic_branch master` then checkout the new branch with `git
+    checkout my_topic_branch`.  Please avoid working directly on the
+    `master` branch.
+* Make commits of logical units.
+* Make sure your code conforms to the [styleguide][styleguide].
+* Format the codes using `clang-format -i -style=file <file name>` before committing. To format all the files, you can use scripts/clang-format/run-clang-format.sh (or .bat for Windows).
+
+
+## Submitting Changes
+
+* Push your changes to a topic branch in your fork of the repository.
+* Submit a pull request to the main repository.
+
+# Additional Resources
+
+* [General GitHub documentation](http://help.github.com/)
+* [GitHub pull request documentation](http://help.github.com/send-pull-requests/)
+* [OGS Styleguide][styleguide]
+
+[styleguide]: http://ufz.github.com/styleguide/cppguide.xml