diff --git a/README.md b/README.md
index 8560f95..f479d6e 100644
--- a/README.md
+++ b/README.md
@@ -1,28 +1,92 @@
 # SendgridNotification
-Short description and motivation.
 
-## Usage
-How to use my plugin.
+SendgridNotification is mountable engine of Ruby on Rails, and
+notification mail (e.g. account registration, logging in by new devise,
+reminder, etc...) sender and utility, using SendGrid API.
 
-## Installation
-Add this line to your application's Gemfile:
+This provides mail utility models, migrations, and rake tasks.
+
+## Installation / Usage
+
+First, add sendgird_notification in Gemfile
 
 ```ruby
 gem 'sendgrid_notification'
 ```
 
-And then execute:
-```bash
-$ bundle
+```sh
+bundle install
+```
+
+Then, generate migration files and migrate
+
+```sh
+bin/rails sendgrid_notification_engine:install:migrations
+bin/rails db:migrate
+```
+
+Generate and edit controllers for NotificationMail CRUD
+
+```
+...
+```
+
+Create NotificationMail record. key = 'example'
+
+
+```
+...
 ```
 
-Or install it yourself as:
-```bash
-$ gem install sendgrid_notification
+And send the mail
+
+```
+...
 ```
 
+Oops. It lacks SendGrid API configuration. Get API key from sendgrid.com and set it ENV['SENDGRID_API_KEY']
+
+
+```
+...
+```
+
+### Make subclasses for each notification_mail key
+
+```
+...
+```
+
+### Validate mail template has right parameter name
+
+```
+...
+```
+
+## Configuration
+
+| Name | Description | Default Value |
+|------|-------------|---------------|
+| config.sendgrid_notification.api_key | SendGrid API Key | `ENV['SENDGRID_API_KEY']` |
+| config.sendgrid_notification.mail_from | FROM address of notification mail | `ENV['SENDGRID_MAIL_FROM']` |
+| config.sendgrid_notification.mail_from_name | FROM name of notification mail | `ENV['SENDGRID_MAIL_FROM_NAME']` |
+| config.sendgrid_notification.mailer | Mailer class name (by string). usually no need to change | `"SendgridNotification::SendgridMailer"` |
+
+## Rake tasks
+
+| Task | Description | ENV/Parameter  |
+|------|-------------|----------------|
+| sendgrid_notification:send | Send mail  | TO=[recipient email address] KEY=[mail type key] ... and mail parameters  |
+| sendgrid_notification:status:autoupdate | Update status from previous autoupdate task | |
+| sendgrid_notification:status:retrieve   | Only retrieve suppression statuses in start..end | start=[datetime] end=[datetime] |
+| sendgrid_notification:status:update     | Retrieve suppression status and update record | start=[datetime] end=[datetime] |
+| sendgrid_notification:testmail:init | Create notification_mails test record. default key = "_test" |
+| sendgrid_notification:testmail:send | Send testmail | TO=[recipient email address] [body=body] |
+
 ## Contributing
+
 Contribution directions go here.
 
 ## License
+
 The gem is available as open source under the terms of the [MIT License](http://opensource.org/licenses/MIT).