How to write a PR contributing (moving to a fork) tutorial

CONTRIBUTING.md

@@ -4,22 +4,46 @@ While we are seeding this project with an initial set of popular tasks and a few
 models and examples, ongoing contributions from the research community are
 desired to increase the pool of tasks, models, and baselines.
 
+
 ## Pull Requests
 We actively welcome your pull requests.
 
-1. Fork the repo and create your branch from `master`. Set up your environment
-   and run `pre-commit install` once.
-2. Link [CircleCI](https://circleci.com/vcs-authorize/) to your github account 
-   if you haven't done so previously (and make sure the CircleCI tests run 
-   successfully).
-3. If you've added code that should be tested, [add tests](http://parl.ai/docs/tutorial_tests.html).
-4. If you've changed APIs, update the documentation.
-5. Autoformat and lint your code (`bash autoformat.sh`)
-6. Ensure the test suite passes. Run `python -m pytest -m unit`.
-7. If you've added a new dataset, you should also run
+1. Fork the repo and then clone the forked repository. (See this [github guide](https://guides.github.com/activities/forking/) on forking for more info).  
+   **If you have already cloned the repo directly and committed changes, follow the steps in the [section below](#moving-changes-youve-committed-to-a-fork)**
+2. Create your branch from `master`. Set up your environment
+   and run `pre-commit install` once. 
+3. Make your changes
+4. If you've added code that should be tested, [add tests](http://parl.ai/docs/tutorial_tests.html).
+5. If you've changed APIs, update the documentation.
+6. Autoformat and lint your code (`bash autoformat.sh`)
+7. Ensure the test suite passes. Run `python -m pytest -m unit`.
+8. If you've added a new dataset, you should also run
    `python -m pytest -m data`. Copy-paste the output into a comment in your PR.
-8. If you haven't already, complete the Contributor License Agreement ("CLA").
-9. Once the PR is accepted and CI is passing, we will merge the PR for you.
+9. If you haven't already, complete the Contributor License Agreement ("CLA").
+10. Link [CircleCI](https://circleci.com/vcs-authorize/) to your github account 
+   if you haven't done so previously (and make sure the CircleCI tests run 
+   successfully on the PR after you push your changes).
+11. Push your changes!
+12. Once the PR is accepted and CI is passing, we will merge the PR for you.
+
+### Moving changes you've committed to a fork
+1. Fork the repo
+2. In your local repo, rename your origin remote to upstream 
+   ```
+   git remote rename origin upstream
+   ```
+3. Point origin to the forked repo (instead of to the original repo)
+   ```
+   git remote add origin git@github...<FORK>
+   ```
+4. Fetch from the new origin
+   ```
+   git fetch origin
+   ```
+5. Make your local branch track the remote branch (of the forked repo) 
+   ```
+   git branch --set-upstream-to origin/master master
+   ```
 
 ## Contributor License Agreement ("CLA")
 In order to accept your pull request, we need you to submit a CLA. You only need