Finally I found answer myself. To add new icons in 2.3.2 bootstrap we have to add Font Awsome css in you file. After doing this we can override the styles with css to change the color and size.
<link href="http://netdna.bootstrapcdn.com/font-awesome/3.2.1/css/font-awesome.css" rel="stylesheet">
CSS
.brown{color:#9b846b}
If we want change the color of icon then just add brown class and icon will turn in brown color. It also provide icon of various size.
HTML
<p><i class="icon-camera-retro icon-large brown"></i> icon-camera-retro</p> <!--brown class added--> <p><i class="icon-camera-retro icon-2x"></i> icon-camera-retro</p> <p><i class="icon-camera-retro icon-3x"></i> icon-camera-retro</p> <p><i class="icon-camera-retro icon-4x"></i> icon-camera-retro</p>