Add fuller version of navigation instructions

Several steps were missing from the instructions; this commit adds
more detail.

doc/system_hooks/system_hooks.md

@@ -48,6 +48,17 @@ NOTE:
 We follow the same structure and deprecations as [Webhooks](../user/project/integrations/webhooks.md)
 for Push and Tag events, but we never display commits.
 
+## Create a system hook
+
+To create a system hook:
+
+1. In the top navigation bar, go to **{admin}** **Admin Area**.
+1. In the left sidebar, select **System Hooks**.
+1. Provide the **URL** and **Secret Token**.
+1. Select the check box next to each **Trigger** you want to enable.
+1. Select **Enable SSL verification**, if desired.
+1. Click **Add system hook**.
+
 ## Hooks request example
 
 **Request header**: