Pull request review instructions

CONTRIBUTING.md

@@ -243,3 +243,35 @@ Additional hooks are [available](https://github.com/pre-commit/pre-commit-hooks#
 These are configured in `.pre-commit-config.yaml`.
 SPRAS also runs [`ruff`](https://github.com/charliermarsh/ruff) as part of the pre-commit hooks to perform the Python code analysis, which supports many more [rules](https://beta.ruff.rs/docs/rules/).
 These are configured in `pyproject.toml`.
+
+## Reviewing pull requests
+Contributors may help review pull requests from other contributors.
+Part of the review process includes running the updated code locally.
+This requires checking out a branch from the other contributor's fork.
+
+We'll use pull request [170](https://github.com/Reed-CompBio/spras/pull/170) as an example from the `ntalluri` fork with branch `implement-eval`.
+First, you need to add the `ntalluri` fork as a git remote from the command line so that you can pull branches from it.
+```
+git remote add ntalluri https://github.com/ntalluri/spras.git
+```
+The first `ntalluri` is the name we give to the new remote.
+It doesn't have to match the GitHub user name, but that is a convenient convention.
+
+Then, confirm the new remote was added
+```
+git remote -v
+```
+You should see the new remote along with your `origin` remote and any others you added previously.
+Now you can pull and fetch branches from any of these remotes and push to any remotes where you have permissions.
+
+To checkout the branch in the pull request locally run
+```
+git fetch ntalluri
+git checkout implement-eval
+```
+Optionally run
+```
+git log
+```
+To confirm that the most recent commit matches the most recent commit in the pull request.
+Now your local version of SPRAS matches the code in the pull request and you can test the code to confirm it runs as expected.