Add detail on how PR can be submitted. (#79)

* Add detail on how PR can be submitted.

* Address comments

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CONTRIBUTING.md

@@ -1,8 +1,13 @@
-# How to contribute
+# How to Contribute
 
 We'd love to accept your patches and contributions to this project. There are
 just a few small guidelines you need to follow.
 
+* [Contributor License Agreement](#contributor-license-agreement)
+* [Style Guideline and Conventions](#style-guideline-and-conventions)
+* [How to Submit A Pull Request](#how-to-submit-a-pull-request)
+* [Contact Us](#contact-us)
+
 ## Contributor License Agreement
 
 Contributions to this project must be accompanied by a Contributor License
@@ -15,10 +20,114 @@ You generally only need to submit a CLA once, so if you've already submitted one
 (even if it was for a different project), you probably don't need to do it
 again.
 
-## Code reviews
+## Style Guideline and Conventions
+
+In order to maintain consistency, style guidelines as suggested by the
+[Google Python Style Guide] should be followed, as well as conforming to
+the existing styles in the current codebase.
+
+## How to Submit A Pull Request
+
+1. Consult [GitHub Help] for more information on using pull requests.
+
+2. Fork the project, clone your fork to a local repository, and configure
+the upstream remote.
+
+    ```
+    # Fork the project via GitHub UI.
+
+    # Clone your forked repository into local directory.
+    $ git clone <url of forked repository>
+
+    # Navigate to your newly cloned directory.
+    $ cd <path to you local cloned repository>
+
+    # Assign the original repository to a remote called "upstream".
+    # Using HTTPS
+    $ git remote add upstream https://github.com/GoogleCloudPlatform/forseti-security.git
+
+    # Using SSH
+    $ git remote add upstream git@github.com:GoogleCloudPlatform/forseti-security.git
+
+    # Verify new upstream remote is added correctly.
+    $ git remote -v
+
+    origin  git@github.com:<my_fork> (fetch)
+    origin  git@github.com:<my_fork> (push)
+    upstream  git@github.com:GoogleCloudPlatform/forseti-security.git (fetch)
+    upstream  git@github.com:GoogleCloudPlatform/forseti-security.git (push)
+    ```
+
+3. Get the latest changes from the upstream origin into your
+cloned repository.
+
+    ```
+    $ git fetch upstream
+    $ git checkout master
+    $ git merge upstream/master
+    ```
+
+4. Create a new local development branch that will contain your feature,
+or bug fix.
+
+    ```
+    $ git checkout -b <my_development_branch>
+    ```
+
+5. Create your change.
+
+    A change should be a logical, self-contained unit of work, feature, or fix.
+    This way, it is easier for troubleshooting and rollbacks.  In other words,
+    please do not incorporate multiple changes in one PR.
+
+    [Instructions to execute the tools.]
+
+6. Create your test.
+
+    We strive to have high and useful coverage by unit tests.  If your change
+    involves substantial logic, we will request that you write applicable unit
+    tests.
+
+    Our unit tests are written with google-apputils basetest framework.
+    See a [basic example] of how to use it, in the "Google-Style Tests" section.
+
+    [Instructions to run the tests.]
+
+7. Commit your changes and push your development branch to your fork.
+
+    ```
+    $ git push origin <my_development_branch>
+    ```
+
+8. Open a Pull Request.
+
+    Use the GitHub UI to open a pull request.  The GitHub UI will show you
+    dropdowns to select the destination of the pull request:
+    * the base fork is the upstream
+    * the head fork is the user's fork
+
+    All tests must pass before we will review the PR.
+
+9. Code Reviews
+
+    All submissions, including submissions by project members, require review.
+    To begin the review process, create a new GitHub pull request.  The GitHub UI
+    will show if there are any merge conflict(s) to be resolved.
+
+10. Merging your PR.
+
+    Once your PR is approved, we will merge your PR.  Make sure any merge
+    conflict(s) is resolved, if necessary.  We will use the "Squash and Commit"
+    option for merging your PR.  This allows us to squash down your commit
+    histories, and merge with one clean commit.
 
-All submissions, including submissions by project members, require review. We
-use GitHub pull requests for this purpose. Consult [GitHub Help] for more
-information on using pull requests.
+## Contact Us
+Reach out to us with questions by contacting
+[forseti-security@google.com].
 
 [GitHub Help]: https://help.github.com/articles/about-pull-requests/
+[Google Python Style Guide]: https://google.github.io/styleguide/pyguide.html
+[Instructions to execute the tools.]: https://github.com/GoogleCloudPlatform/forseti-security/blob/master/google/cloud/security/README.md#execution
+[basic example]: https://pypi.python.org/pypi/google-apputils
+[Instructions to run the tests.]: https://github.com/GoogleCloudPlatform/forseti-security/blob/master/google/cloud/security/README.md#tests
+[forseti-security@google.com]: mailto:forseti-security@google.com