diff --git a/special-pages/pages/new-tab/app/customizer/customizer.md b/special-pages/pages/new-tab/app/customizer/customizer.md
index 88f71c7ba4..9c84460d48 100644
--- a/special-pages/pages/new-tab/app/customizer/customizer.md
+++ b/special-pages/pages/new-tab/app/customizer/customizer.md
@@ -22,13 +22,121 @@ title: Customizer
   ],
   "widgetConfigs": [
     { "id": "favorites", "visibility": "visible" },
-    { "id": "privacyStats", "visibility": "visible" },
+    { "id": "privacyStats", "visibility": "visible" }
   ],
   "settings": {
     "customizerDrawer": {
       "state": "enabled"
     }
+  },
+  "customizer": {
+    "userImages": [],
+    "theme": "dark",
+    "background": { "kind": "default" }
   }
 }
 ```
 
+## Initial Data
+
+- Add the key `customizer` to `initialSetup`
+- The data takes the following form: {@link "NewTab Messages".CustomizerData}
+- Example from `initialSetup`
+
+```json
+{
+  "...": "...",
+  "customizer": {
+    "userImages": [],
+    "theme": "dark",
+    "background": { "kind": "default" }
+  }
+}
+```
+
+## Subscriptions
+
+- {@link "NewTab Messages".CustomizerOnBackgroundUpdateSubscription `customizer_onBackgroundUpdate`}.
+    - Sends {@link "NewTab Messages".CustomizerOnBackgroundUpdateSubscribe} whenever needed.
+    - For example:
+    - ```json
+      {
+        "background": { "kind": "color", "value": "color01" }
+      } 
+      ```
+    - ```json
+      {
+        "background": { "kind": "gradient", "value": "gradient01" }
+      } 
+      ```
+    - ```json
+      {
+        "background": { "kind": "hex", "value": "#cacaca" }
+      } 
+      ```
+    - ```json
+      {
+        "background": { "kind": "default" }
+      } 
+      ```
+    - ```json
+      {
+        "background": { 
+           "kind": "userImage", 
+           "value": { "id":  "abc", "src": "...", "thumb": "...", "colorScheme": "light" } 
+        }
+      } 
+      ```
+      
+- {@link "NewTab Messages".CustomizerOnImagesUpdateSubscription `customizer_onImagesUpdate`}.
+    - Sends {@link "NewTab Messages".CustomizerOnImagesUpdateSubscribe} whenever needed.
+    - For example, this would be pushed into the page following a successful upload
+      - Note: In that situation, you'd send this followed by `customizer_onBackgroundUpdate` above
+    - For example:
+    - ```json
+      {
+        "userImages": [{"id":  "abc", "src": "...", "thumb": "...", "colorScheme": "light" }]
+      } 
+      ```
+      
+- {@link "NewTab Messages".CustomizerOnThemeUpdateSubscription `customizer_onThemeUpdate`}.
+    - Sends {@link "NewTab Messages".CustomizerOnThemeUpdateSubscribe} whenever needed.
+    - For example:
+    - ```json
+      {
+        "theme": "system"
+      } 
+      ```
+
+## Notifications
+
+- {@link "NewTab Messages".CustomizerSetBackgroundNotification `customizer_setBackground`}.
+    - Sends {@link "NewTab Messages".CustomizerSetBackgroundNotify} whenever needed.
+    - For example:
+    - ```json
+      {
+        "background": { "kind": "color", "value": "color01" }
+      } 
+      ```
+
+- {@link "NewTab Messages".CustomizerSetThemeNotification `customizer_setTheme`}.
+    - Sends {@link "NewTab Messages".CustomizerSetBackgroundNotify} whenever needed.
+    - For example:
+    - ```json
+      {
+        "theme": "light"
+      } 
+      ```
+
+- {@link "NewTab Messages".CustomizerUploadNotification `customizer_upload`}.
+    - Sent to trigger a file upload
+
+
+- {@link "NewTab Messages".CustomizerDeleteImageNotification `customizer_deleteImage`}.
+    - Sends {@link "NewTab Messages".CustomizerDeleteImageNotify} whenever needed.
+    - For example:
+    - ```json
+      {
+        "id": "abc"
+      } 
+      ```