diff --git a/_subsections/chapter03.org b/_subsections/chapter03.org
index d13e2ae..9c63074 100644
--- a/_subsections/chapter03.org
+++ b/_subsections/chapter03.org
@@ -151,6 +151,9 @@ b. lighter group:
 -
   [[../_share/media/img/cameraraw-color-temperature.jpg]]
 
+** layer styles
+- fill only affects the main image, but will leave layers styles alone
+
 * Timestamp
 #+ATTR_HTML: :class content
 - [[https://youtu.be/ok9cVCETDeE?si=Lj4fPVabIC9jBW7O&t=1][00:00 What is Happening?]]
diff --git a/_subsections/chapter04.org b/_subsections/chapter04.org
new file mode 100644
index 0000000..8a32cf1
--- /dev/null
+++ b/_subsections/chapter04.org
@@ -0,0 +1,28 @@
+#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="../../../../_share/media/css/org-mode.css" />
+#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="../../../../_share/media/css/graphics.css" />
+#+title: Notes on Lesson 04 - Layer Mask | PiXimperfect
+
+[[../photoshop-for-complete-beginners.org][<Back to Main Section]]
+
+* Downloads
+- Practice Files: https://bit.ly/44aHY3c
+
+* Notes
+
+* Playlist
+
+#+ATTR_HTML: :class playlist
++ [[https://youtu.be/aNpO6G72O3w?si=OYj36t6pnG6zpXIm][00:00 What Are Layer Masks?]]
++ [[https://youtu.be/aNpO6G72O3w?si=CaHdFgVM5pw_fgp0&t=178][02:58 Important Downloads & Announcements]]
++ [[https://youtu.be/aNpO6G72O3w?si=pwKG3NNXzp8NsGN-&t=209][03:29 Why Use A Layer Mask?]]
++ [[https://youtu.be/aNpO6G72O3w?si=D0ZVdRvBZ9jrjm-n&t=227][03:47 Reason 1: Non-Destructive Abilities]]
++ [[https://youtu.be/aNpO6G72O3w?si=w8aLyeLpyyqeX5G9&t=474][07:54 Reason 2: Compatibility with Non-Raster Layer]]
++ [[https://youtu.be/aNpO6G72O3w?si=cHwwjgjcbIvf3Hno&t=686][11:26 Linking & Unlinking Layer Masks]]
++ [[https://youtu.be/aNpO6G72O3w?si=sDBGUsD5CKK_0i1g&t=813][13:33 Turning Off and On]]
++ [[https://youtu.be/aNpO6G72O3w?si=kEM8JPCox3RhIuSq&t=868][14:28 Mask Properties: Feather]]
++ [[https://youtu.be/aNpO6G72O3w?si=G6x177vUaa4TxX4Y&t=1062][17:41 Mask Properties: Density]]
++ [[https://youtu.be/aNpO6G72O3w?si=BIUkibJYNuT6ivq8&t=1184][19:44 Duplicate Masks]]
++ [[https://youtu.be/aNpO6G72O3w?si=X85qg0vdXugnBIR2&t=1295][21:35 Problem with Copying Masks]]
++ [[https://youtu.be/aNpO6G72O3w?si=2EubEOKmDI9dETuQ&t=1417][23:37 Double Masking]]
++ [[https://youtu.be/aNpO6G72O3w?si=QUt_vWIkDL2NfY0h&t=1604][26:44 Image as a Mask]]
++ [[https://youtu.be/aNpO6G72O3w?si=sCtxC5Mbb6xp_wjt&t=1709][28:28 Concept Recap]]
diff --git a/photoshop-for-complete-beginners.org b/photoshop-for-complete-beginners.org
index a8a2aa5..1e178f5 100644
--- a/photoshop-for-complete-beginners.org
+++ b/photoshop-for-complete-beginners.org
@@ -2,6 +2,9 @@
 #+HTML_HEAD: <link rel="stylesheet" type="text/css" href="../../../_share/media/css/graphics.css" />
 #+title: Photoshop for Complete Beginners | PiXimperfect
 
+* Links
+- [[../../course-listings.org][Course Listing]]
+
 * Notes
 
 ** [[./_subsections/chapter02.org][Lesson 02 - Master Layer]]