README.md in a1412tk_bmi-0.0.2 vs README.md in a1412tk_bmi-0.0.3

@@ -1,8 +1,8 @@
 # A1412tkBmi
 
-TODO: Write a gem description
+A simple BMI calculation
 
 ## Installation
 
 Add this line to your application's Gemfile:
 
@@ -18,10 +18,22 @@
 
     $ gem install a1412tk_bmi
 
 ## Usage
 
-TODO: Write usage instructions here
+Simply run `a1412tk_bmi` command with `height` and `weight`:
+
+    $ a1412tk_bmi [height(cm)] [weight(kg)]
+
+Example:
+
+    $ a1412tk_bmi 180 70
+    21.6
+
+Or you can put them as float:
+
+    $ a1412tk_bmi 180.5 70.8
+    21.7
 
 ## Contributing
 
 1. Fork it ( https://github.com/[my-github-username]/a1412tk_bmi/fork )
 2. Create your feature branch (`git checkout -b my-new-feature`)