How To Stop Google Bots From Indexing The Following Page?

My site http://www.quickhaggle.com is built on Yii Framework. I have notice that a page is accessed through different URLs which is actually creating "duplicate content issue" for the site.

For example

The original page:- http://www.quickhaggle.com/offer/I-am-looking-for-a-Wedding-Planner,-i-am-a-Financial-Adviser-26.htm

Which is also accessible through the following URLs.

http://www.quickhaggle.com/offer/I-am-looking-for-a-Wedding-Planner,-i-am-a-Financial-Adviser-26.htm?area=New+Zealand

http://www.quickhaggle.com/offer/I-am-looking-for-a-Wedding-Planner,-i-am-a-Financial-Adviser-26.htm?route=offer%2FI-am-looking-for-a-Wedding-Planner%2C-i-am-a-Financial-Adviser-26.htm&area=New+Zealand&MPublicMessagesForm_page=2

http://www.quickhaggle.com/offer/I-am-looking-for-a-Wedding-Planner,-i-am-a-Financial-Adviser-26.htm?route=offer%2FI-am-looking-for-a-Wedding-Planner%2C-i-am-a-Financial-Adviser-26.htm&area=New+Zealand&MPublicMessagesForm_page=3

http://www.quickhaggle.com/offer/I-am-looking-for-a-Wedding-Planner,-i-am-a-Financial-Adviser-26.htm?route=offer%2FI-am-looking-for-a-Wedding-Planner%2C-i-am-a-Financial-Adviser-26.htm&area=New+Zealand&MPublicMessagesForm_page=4

Other Variation

http://www.quickhaggle.com/print-ad/I-am-looking-for-a-Wedding-Planner,-i-am-a-Financial-Adviser-26.htm

http://www.quickhaggle.com/share-ad-with-friend/I-am-looking-for-a-Wedding-Planner%2C-i-am-a-Financial-Adviser-26.htm

What entries I need to mention in the Robots.txt file to stop google from indexing all these variations. I will appreciate your help in this matter.

Thank you in advance.

I just heard in Google Support Forum that adding rel="canonical tag in the <head> section can stop google from indexng similar pages.

But I am little confused about the exact rel="canonical code I need in the <head> section.

/* moved to General Discussion */

(not regarding The Yii Project Site)

tri@ Thank you.

Waiting for someone reply.