diff --git a/README.md b/README.md
index e2b00ed..54a7abf 100644
--- a/README.md
+++ b/README.md
@@ -1,11 +1,13 @@
 Web-based Desktop Client for [Mastodon][]
 =========================================
 
+<img src="https://github.com/rhysd/ss/blob/master/Mstdn/main.png?raw=true" width="484" alt="screen shot"/>
+
 Features:
 
 - [x] Small window on your menubar (or isolated window)
 - [x] Desktop notification
-- [ ] Customizable shortcut keybinds
+- [x] Customizable shortcut keybinds
 - [ ] Multi-account
 
 Mastodon is an open source project. So if you want to make a new UI, you can just fork the project,
@@ -20,7 +22,6 @@ provides a way to do it.
 
 ```
 $ npm install -g mstdn
-$ open-mstdn-app
 ```
 
 ### As an isolated app
@@ -29,7 +30,15 @@ Download a package archive from [Release page][] (not yet), put unarchived app t
 
 ## Usage
 
-To be written.
+If you installed this app via npm, below command is available to start app.
+
+```
+$ open-mstdn-app
+```
+
+At first, a dialog which recommends to write up config is shown and JSON config file will be shown in your editor. You need to fill up '"name"' and `"host"` keys in `"accounts"`.
+
+Then please try to start app again. Usage is the same as web client on mobile devices. Some shortcuts are available by default (please see below 'Customization' section).
 
 ## Customization
 
@@ -41,8 +50,58 @@ The `{app dir}` is:
 - `~/.config/Mstdn` for Linux
 - `%APPDATA%\Mstdn` for Windows.
 
+The JSON file can contain below key-values:
+
+### `hot_key`
+
+`hot_key` is a key sequence to toggle application window. The shortcut key is defined globally.
+The format is a [Electron's accelerator](https://github.com/electron/electron/blob/master/docs/api/accelerator.md). Please see the document to know how to configure this value.
+Default value is `"CmdOrCtrl+Shift+S"`. If you want to disable, please set empty string or `null`. 
+
+### `icon_color`
+
+Color of icon in menubar. `"black"` or `"white"` can be specified.
+
+### `always_on_top`
+
+When this value is set to `true`, the window won't be hidden if it loses a focus. Default value is `false`.
+
+### `normal_window`
+
+When this value is set to `true`, application will be launched as a normal window application.
+If menu bar behavior does not work for you, please use set this value to `true` to avoid it.
+Default value is `false` on macOS or Linux, `true` on Windows because window position is broken in some version of Windows.
+
+### `zoom_factor`
+
+Font zoom factor in application. It should be positive number. For example, `0.7` means `70%` font zooming.
+Default font size is a bit bigger because https://mobile.twitter.com is originally for mobile devices. So default value is `0.9`.
+
+### `accounts`
+
+Array of your accounts. An element should has `"name"`, `"host"` and `"default_page"` keys. `"name"` represents your screen name. `"host"` represents a host part of URL of your mastodon instance. `"default_page"` is a page firstly shown.
+
+You need to write up this config at first.
+
+### `keymaps`
+
+Object whose key is a key sequence and whose value is an action name.
+
+| Action Name        | Description                     | Default Key |
+|--------------------|---------------------------------|-------------|
+| `scroll-down`      | Scroll down window              | `j`         |
+| `scroll-up`        | Scroll up window                | `k`         |
+| `scroll-top`       | Scroll up to top of window      | `i`         |
+| `scroll-down-page` | Scroll down to bottom of window | `m`         |
+
+If an action name starts with `/`, it will navigate to the path. For example, if you set `"/web/timelines/home"` to some key shortcut and you input the key, browser will navigate page to `https://{your host}/web/timelines/home`.
+
+By default, some key shortcuts are set.
+
 ## Multi account
 
+Not yet.
+
 [Mastodon]: https://github.com/tootsuite/mastodon
 [npm]: https://www.npmjs.com/package/mstdn
 [Release page]: https://github.com/rhysd/Mstdn