Hi Lemba,
Please go to Settings/Extensions and Activate Google Integration [please see the attachment ].
I can suggest watching this video - > http://www.clarizen.com/appsmarketplace/item/Google-Docs-Integration.html
You can also find more information here -> http://usermanual.clarizen.com/#collaboration-items
Since Clarizen invites invites you to an interactive, real-time demonstration of our features, please feel free to join our webinars -> http://www.clarizen.com/resources/online-demo.html#second. These are great tools for free consulting and visual answers to your questions.
In case of further questions, please contact me.
Thank you.