update README

Author: zbryikt

README.md

@@ -2,6 +2,32 @@
 
 CSS for button that loads. check https://loading.io/button/ for more information.
 
+# usage
+
+1. include ldbtn.css and loading.:
+
+    <link rel="stylesheet" type="text/css" href="https://cdn.jsdelivr.net/gh/loadingio/[email protected]/dist/ldbtn.css"/>
+
+
+2. add class for one of the desired effect to your button, along with a loader inside:
+
+    <div class="btn btn-primary ld-ext-right">
+      <div class="ld ld-ball ld-bounce"></div>
+    </div>
+
+  - The *ld-ball* and *ld-bounce* classes used here are from [loading.css](https://loading.io/animation/). You can use your own animation.
+  - The class *ld* is required for loading buttons to identify the loader element.
+
+3. Trigger the loading animation by adding "running" class in the button:
+
+    <div class="btn btn-primary ld-ext-right running">
+      <div class="ld ld-ball ld-bounce"></div>
+    </div>
+ 
+You can also use [ldLoader](https://loading.io/lib/loader/) to manipulate loader's state.
+
+For more information about how to use loading buttons, please check the [online documentation here](https://loading.io/button/).
+
 
 # License