Do you have any programming background? (PHP is probably best)
If you dont then its best to first learn to code.
If you have a few years programming then you could start reading the FB API docs.
Write some simple apps at first then move on to more complex apps.

Chaitanya,

If you know HTML and CSS, you can make a basic facebook application. Obviously it won’t do anything really cool and will just be static but that may be enough to get you started doing more complicated things. An app is essentially a web page displayed through Facebook.

Here is a tutorial on how to make one,

Developing a Facebook Application for absolute beginners - Emanuele Feronato

Hope that helps,

Shawn

Thanks For your help .