How To Send Free SMS Using Gmail

How to send free SMS in gmail?
Login to your Gmail account 
Go to "Settings"  
Click on "Labs" tab  
Enable SMS (text messaging) in Chat  
Click on Save Changes

Type your Friend's phone number in chat box and click on Send SMS

After that type your friend's name and click on Save

Then chat window will open with the particular phone number. Now type your message and press Enter.

Thats All...