Vikash, please read the help before you post here. What you’re looking for is on this website – http://labs.google.co.in/smschannels/help?cr=in#g00

All you need to do is send an sms that has the following text –
send

Where is your Channel’s name and
is the text you want to post to your Channel.

Also, please read the rest of the help and you’ll be able to resolve most of your issues. Enjoy 🙂