diff --git a/src/conduit/DiagramUploadConduitAPIMethod.php b/src/conduit/DiagramUploadConduitAPIMethod.php
index e8cfa86..d2d6f46 100644
--- a/src/conduit/DiagramUploadConduitAPIMethod.php
+++ b/src/conduit/DiagramUploadConduitAPIMethod.php
@@ -1,127 +1,176 @@
 <?php
 
 final class DiagramUploadConduitAPIMethod extends ConduitAPIMethod {
 
   /**
    * Name of the Conduit API method.
    * This method should return a string that represents the name of the method.
    * The method name is used to identify the method when calling it via the
    * Conduit API.
    */
   public function getAPIMethodName() {
     return 'diagram.upload';
   }
 
   /**
    * Defines the input parameters for this API.
    * This method should return an associative array where the keys are
    * the names of the parameters and the values are strings that describe
    * the types of the parameters.
    * The parameter types are used for documentation purposes and are displayed
    * on the documentation page for the method to help users understand what
    * kind of data they can pass to the method when calling it.
    */
   protected function defineParamTypes() {
     return array(
       'data_base64' => 'required nonempty base64-bytes',
       'id' => 'optional id of diagram to be updated',
       'viewPolicy' => 'optional valid policy string or <phid>',
     );
   }
 
   /**
    * This method should return a string that describes the type of data that
    * the method returns.
    * The return type is used for documentation purposes and is displayed on the
    * documentation page for the method to help users understand what kind of
    * data they can expect to receive when calling the method.
    */
   protected function defineReturnType() {
     return 'nonempty guid';
   }
 
   /**
    * The execute method is the core of your Conduit API method and is where
    * you implement the logic that performs the desired operation.
    *
    * The execute method should return the result of the operation in a
    * format that can be serialized as JSON.
    * The result will be sent back to the client as the response to the API
    * request.
    */
   protected function execute(ConduitAPIRequest $request) {
     $viewer = $request->getUser();
     $base64_data = $request->getValue('data_base64');
     $diagram_id = $request->getValue('id');
 
     if ($diagram_id) {
       // check if we are trying to save the same data as the current data
       $diagram = id(new DiagramVersion())->loadLatestByDiagramID($diagram_id);
       if ($diagram !== null) {
         $data = $diagram->getData();
         $old_base64_data = base64_encode($data);
 
         if (DiagramController::equalPngMetaData($base64_data, $old_base64_data)) {
           return array(
             'result' => $diagram->getPHID(),
             'id' => $diagram->getDiagramID(),
             'error_code' => null,
             'error_info' => null
           );
         }
       }
     }
 
     // verify if the uploaded data really contains a drawio diagram
     if (DiagramController::isDrawioPngBase64($base64_data) == false) {
       return array(
         'result' => null,
         'id' => null,
         'error_code' => -1,
         'error_info' => 'invalid base64 data'
       );
     }
 
     // Set the options for the new file
     $options = array(
       'name' => 'diagram.png',
       'viewPolicy' => PhabricatorPolicies::POLICY_USER,
       'mime-type' => 'image/png',
       'actor' => $this->getViewer(),
       'diagramID' => $diagram_id
     );
 
     try {
       // Create the new file object
       $diagram = DiagramVersion::newFromFileData($base64_data, $options);
 
       $diagram->publishNewVersion($request, $diagram->getDiagramID());
 
       return array(
         'result' => $diagram->getPHID(),
         'id' => $diagram->getDiagramID(),
         'error_code' => null,
         'error_info' => null
       );
     } catch (Exception $e) {
       // error occurred during saving
       return array(
         'result' => null,
         'id' => null,
         'error_code' => $e->getCode(),
         'error_info' => $e->getMessage()
       );
     }
   }
 
   /**
    * Descriptive text what this Conduit API method does
    * This method should return a string that describes what the method does.
    * The method description is used for documentation purposes and is
    * displayed on the documentation page for the method to help users
    * understand what the method does and how to use it.
    */
   public function getMethodDescription() {
-    return pht('Upload a diagram to the server.');
+    return pht("Upload a diagram to the server.");
+  }
+
+  /**
+   * Generates custom documentation pages for this Conduit API method.
+   * This method should return an array of PhabricatorDocumentationBoxPage
+   * objects representing the custom documentation pages you want to add for
+   * the method.
+   * Each PhabricatorDocumentationBoxPage object represents a single
+   * documentation page and includes a title and content.
+   */
+  public function newDocumentationPages(PhabricatorUser $viewer) {
+    $pages = array();
+
+    // create different chapters
+    $pages[] = $this->getDocumentationUsage($viewer);
+
+    return $pages;
+  }
+
+  /**
+   * Creates the documentation chapter about Usage
+   */
+  public function getDocumentationUsage(PhabricatorUser $viewer) {
+    // set title and content of 'Usage' documentation box
+    $title = pht('Usage');
+    $content = pht(<<<EOREMARKUP
+IMPORTANT: when sending Base64 encoded data in `data_base64` using the
+`application/x-www-form-urlencoded` content type, the `+` character is used to
+represent a space character. To ensure that the `+` character is correctly
+interpreted by the server as a `+` character and not a space character, it
+should be URL-encoded as **%%2B**
+EOREMARKUP
+    );
+
+    // format content
+    $content = $this->newRemarkupDocumentationView($content);
+
+    // create documentation box
+    $page = $this->newDocumentationBoxPage(
+      $viewer,
+      $title,
+      $content
+    );
+
+    // set icon and anchor of documentation box for navigation menu on the left
+    $page->setAnchor('usage');
+    $page->setIconIcon('fa-warning');
+
+    return $page;
   }
 }