diff --git a/doc/index.rst b/doc/index.rst
index 916a044..053f362 100644
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -1,8 +1,14 @@
 ChronoChat Manual
 ===================================================================
 
-Step 0. Before open ChronoChat, make sure ndnd is running on your machine, and your default key and certificate have been generated and installed . 
-1. When you open ChronoChat App, you will see a contact panel as shown below.
+Step 0. Before open ChronoChat, make sure ndnd is running on your machine. 
+If you have installed `NDNx Control Center`_, check if its tray icon shows up
+
+.. _NDNx Control Center: http://named-data.net/download/
+
+ and your default key and certificate have been generated and installed . 
+
+Step 1. When you open ChronoChat App, you will see a contact panel as shown below.
 
 .. image:: https://raw.github.com/bruinfish/ChronoChat-V2/master/doc/img/chronochat-1.png