CASSANDRA-19777: Update doc page for how-to commit with more intro

site-content/source/modules/ROOT/pages/development/how_to_commit.adoc

@@ -4,10 +4,35 @@
 
 Commits applicable to multiple versions are atomically pushed forward merges.
 
-The fix lands on the oldest release branch and is then forward-merges it into each newer branch using an ours merge to record branch lineage and amends that merge commit to include the branch-appropriate patch.
+Fixes are applied first on the oldest applicable release branch, and are then forward-merged onto each newer branch using an ours merge strategy to record branch lineage.  Each forward-merge commit contains the branch-appropriate patch.
 
 This keeps a clean, traceable history and a single logical unit of work per ticket per branch, while preventing unintended diffs from being pulled forward automatically.
 
+== Introduction for New Committers
+
+Patches are applied using git command lines, not via github UI.  The following outlines the simple trunk-only patch workflow.  See next section for multi-branch contributions.
+
+Development branches are kept in forks.  The upstream apache/cassandra repository is reserved for trunk and release branches.
+
+Use the following Git CLI commands when merging a PR:
+
+Step 1: From your project repository, check out a new branch and test the changes.
+[source,shell]
+----
+git checkout -b <jira>/<branch> <branch>
+----
+
+Step 2: Squash, fast-forward merge, and update on GitHub following the project workflow.
+[source,shell]
+----
+git switch trunk
+# there should only be one commit, squashed 
+git cherry-pick <jira>/<branch>
+git push --atomic origin trunk -n
+# check dry-run looks correct
+git push --atomic origin trunk
+----
+
 == Git branch based Contribution
 
 How to commit and merging git-based contributions.