Add basic install guide

1 files changed, 56 insertions, 1 deletions

diff --git a/README.md b/README.md
index 07e2238c34..9c0b8d777b 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,56 @@
-# activetext
+# Active Text
+
+🤸‍♂️💰📝
+
+## Installing
+
+Assumes a Rails 5.2+ application with Active Storage and Webpacker installed.
+
+1. Install the gem:
+
+   ```ruby
+   # Gemfile
+   gem "activetext", github: "basecamp/activetext", require: "active_text"
+   gem "mini_magick" # for Active Storage variants
+   ```
+
+1. Install the npm package:
+
+  ```js
+  // package.json
+  "dependencies": {
+    "activetext": "basecamp/activetext"
+  }
+  ```
+
+  ```sh
+  $ yarn install
+  ```
+
+  ```js
+  // app/javascript/packs/application.js
+  import "activetext"
+  ```
+
+1. Declare text columns as Active Text attributes:
+
+   ```ruby
+   # app/models/message.rb
+   class Message < ActiveRecord::Base
+     active_text_attribute :content
+   end
+   ```
+
+1. Replace form `text_area`s with `active_text_field`s:
+
+   ```erb
+   <%# app/views/messages/_form.html.erb %>
+   <%= form_with(model: message) do |form| %>
+     …
+     <div class="field">
+      <%= form.label :content %>
+      <%= form.active_text_field :content %>
+     </div>
+     …
+   <% end %>
+   ```