diff --git a/notify.md b/notify.md
index 03923c8..c411321 100644
--- a/notify.md
+++ b/notify.md
@@ -1,6 +1,14 @@
 # Set notification
 
+acme.sh can send notifications in its cronjob. 
+The notifications can be emails for another supported way, such as request to a webhook etc. 
 
+As for now,  there is email notification supported, but there will be more soon. You can also implement your hook.
+
+See example: `mailgun.sh`  or `sendgrid.sh`
+
+
+## Usage:
 ```sh
 acme.sh --set-notify  [--notify-hook mailgun]
 
@@ -30,16 +38,33 @@ acme.sh --set-notify  [--notify-mode 0]
 
 ## 1. Set notification for mailgun.com
 
+Send notification by mailgun.com api. The notification email will be sent to your email address.
+
+Please register a free account at mailgun.com, you will get your api key.
+
+If you don't have a domain, you can use the sandbox domain in your account.
+It looks like `sandbox888888.mailgun.org`.
+If you use the sandbox domain, you must add your receiving email address as an "Authorized recipient"
+https://app.mailgun.com/app/account/authorized
+
+
 ```sh
+#The api key in your account.
 export  MAILGUN_API_KEY="xxxxxxxx"
-export  MAILGUN_API_DOMAIN="xxxxxx.com" 
-export  MAILGUN_FROM="xxx@xxxxx.com"
+
+#The api domain, you can use the sandbox domain in your account.
+export  MAILGUN_API_DOMAIN="xxxxxx.com"
+
+#Optional,  the mail from address. it must be user@MAILGUN_API_DOMAIN
+export  MAILGUN_FROM="xxx@xxxxxx.com"
+
+#The mail to address, which is to receive the notification.
 export  MAILGUN_TO="yyyy@gmail.com"
 
-
+#Optional, if your mailgun account is in eu region, you must set MAILGUN_REGION
 export  MAILGUN_REGION="us|eu"          #optional, use "us" as default
 
-acme.sh --set-notify  --notify-hook mailgun
+acme.sh --set-notify  --notify-hook  mailgun
 ```