diff --git a/README.md b/README.md
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index 0000000..3012800
--- /dev/null
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@@ -0,0 +1,111 @@
+![Docker Pulls](https://img.shields.io/docker/pulls/h3poteto/slack-rage)
+[![GitHub release (latest SemVer)](https://img.shields.io/github/v/release/h3poteto/slack-rage)](https://github.com/h3poteto/slack-rage/releases)
+
+# SlackRage
+
+SlackRage is a Slack bot. It will monitor all messages in participating channels and detects conversational excitement on these channels. It will notify the channel when excitement is detected.
+This command line tool provides two methods to monitor Slack channels. First one is using RTM, and another one is using Slack Event API.
+
+## Usage
+
+```
+$ ./slack-rage --help
+Notify the rage of slack channel
+
+Usage:
+  slack-rage [command]
+
+Available Commands:
+  event       Run webhook server for slack Event API
+  help        Help about any command
+  rtm         Run bot using Real Time Message
+  version     Print the version number
+
+Flags:
+  -h, --help   help for slack-rage
+```
+
+If you want to use RTM, please provide argument:
+
+```
+$ ./slack-rage rtm --help
+Run bot using Real Time Message
+
+Usage:
+  slack-rage rtm [flags]
+
+Flags:
+  -c, --channel string   Notify channel. (default random)
+  -h, --help             help for rtm
+  -p, --period int       Observation period seconds for rage judgement. This CLI notify when there are more than threshold posts per period. (default 60)
+  -t, --threshold int    Threshold for rage judgement. (default 10)
+  -v, --verbose          Enable verbose mode
+```
+
+- `channel` Please specify Slack channel name which you want to be notified.
+- `period` Observation period seconds.
+- `threshold` This CLI notify when there are more than threshold posts per period in a channel.
+
+And `event` command requires same arguments.
+
+## Setup
+You can run this CLI with docker, and start bot using RTM as default.
+
+```
+$ docker run --rm h3poteto/slack-rage ./slack-rage rtm
+```
+
+### RTM
+New Slack App [does not support RTM](https://api.slack.com/rtm), so please create [Classic Slack App](https://api.slack.com/apps?new_classic_app=1).
+
+> New Slack apps may not use any Real Time Messaging API method. Create a classic app and use the V1 Oauth flow to use RTM.
+
+
+After you create a Classic app, you can get `OAuth Access Token` and `Bot User OAuth Access Token`. Please set these token to environment variables.
+
+```
+$ docker run --rm -e SLACK_TOKEN={BotUserOAuthAccessToken} -e OAUTH_TOKEN=${OAuthAccessToken} h3poteto/slack-rage
+```
+
+And please provide these scopes to the app.
+
+- `bot`
+- `channels:history`
+- `channels:read`
+- `chat:write:bot`
+- `user:read`
+
+
+![rtm-scopes](./readme/rtm-scopes.png)
+
+
+Everything ok, please invite this bot user to Slack channels which you want to monitor.
+
+
+### Event API
+Please create a new [Slack App](https://api.slack.com/apps), and you can get `Bot User OAuth Access Token`.
+Please set this token to environment variables.
+
+```
+$ docker run --rm -e SLACK_TOKEN={BotUserOAuthAccessToken} h3poteto/slack-rage event
+```
+
+You have to prepare Web server to receive webhook from Slack Event API. So please run this docker image in your server, and assign DNS, like `slack-rage.example.com`.
+And please set it to RequestURL in Event Subscriptions.
+
+![event-subscription](./readme/event-subscription.png)
+
+Please provide these scopes to the app.
+
+- `channels:history`
+- `channels:read`
+- `chat:write`
+- `users:read`
+
+![event-scopes](./readme/event-scopes.png)
+
+Everything ok, please invite this bot user to Slack channels which you want to monitor.
+
+
+## License
+The package is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).
diff --git a/cmd/event.go b/cmd/event.go
index 72d995d..7dcfb2c 100644
--- a/cmd/event.go
+++ b/cmd/event.go
@@ -23,7 +23,7 @@ func runEventCmd() *cobra.Command {
 	flags := cmd.Flags()
 	flags.IntVarP(&r.threshold, "threshold", "t", 10, "Threshold for rage judgement.")
 	flags.IntVarP(&r.period, "period", "p", 60, "Observation period seconds for rage judgement. This CLI notify when there are more than threshold posts per period.")
-	flags.StringVarP(&r.channel, "channel", "c", "", "Notify channel.")
+	flags.StringVarP(&r.channel, "channel", "c", "random", "Notify channel.")
 	flags.BoolVarP(&r.verbose, "verbose", "v", false, "Enable verbose mode")
 
 	return cmd
diff --git a/cmd/rtm.go b/cmd/rtm.go
index 0b36c62..6d7e924 100644
--- a/cmd/rtm.go
+++ b/cmd/rtm.go
@@ -23,7 +23,7 @@ func runRTMCmd() *cobra.Command {
 	flags := cmd.Flags()
 	flags.IntVarP(&r.threshold, "threshold", "t", 10, "Threshold for rage judgement.")
 	flags.IntVarP(&r.period, "period", "p", 60, "Observation period seconds for rage judgement. This CLI notify when there are more than threshold posts per period.")
-	flags.StringVarP(&r.channel, "channel", "c", "", "Notify channel.")
+	flags.StringVarP(&r.channel, "channel", "c", "random", "Notify channel.")
 	flags.BoolVarP(&r.verbose, "verbose", "v", false, "Enable verbose mode")
 
 	return cmd
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