diff --git a/wp-content/themes/twentynineteen/contributing.txt b/wp-content/themes/twentynineteen/contributing.txt
new file mode 100644
index 0000000000..4cebefc2e7
--- /dev/null
+++ b/wp-content/themes/twentynineteen/contributing.txt
@@ -0,0 +1,19 @@
+=== Contributing to Twenty Nineteen ===
+
+= Compiling SCSS =
+
+Twenty Nineteen relies on Sass, which allows us to more easily share code between multiple stylesheets (style.css, style-editor.css, etc.). To compile Sass files (.scss), use the built-in npm build tool. The build tool will make sure that your compiled CSS code stays in sync and has the correct formatting.
+
+Installation instructions
+
+1. Using a command line interface, go to the “twentynineteen” directory `cd /my-computer/local-wordpress-install/src/wp-content/themes/twentynineteen`.
+
+2. Type `npm install` into the command line, and press the [return] key, to install all Node.js dependencies.
+
+3. The dependencies may take a few minutes to download but once it completes, you’re done.
+
+Usage instructions
+
+1. After making a change to a .scss file, run `npm run build` from within the theme directory to build the CSS files with your new changes. You may need to run the build command twice to update style-rtl.css (because the RTL process might update from style.css before that is updated from Sass file changes).
+
+2. You can also “watch” the theme directory for Sass changes and rebuild the CSS anytime a change occurs by running: `npm run watch`.
diff --git a/wp-includes/version.php b/wp-includes/version.php
index ba03a62115..48907c8358 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.6-beta3-58450';
+$wp_version = '6.6-beta3-58451';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.