Is it possible to use MS WORD PAD in mac book air ?

Yes, you can use Wordpad, and it behaves the same way on a MacBook Air as it does on a non-Apple machine. You just need to install Windows on your Mac:

http://discussions.apple.com/docs/DOC-2741

But as others indicate, that is usually not essential for that utility on a Mac. There are many free and almost free alternatives that are just as functional.

Hello and welcome to Apple communities

Try this Text Wrangler https://itunes.apple.com/fr/app/textwrangler/id404010395?mt=12

WordPad is a Windows-exclusive app, so you cannot use it in OS X. Instead, OS X includes TextEdit (you can find it in /Applications/Utilities), which works in the same way as WordPad.