You have gone through the Add option of the Dockbar. Let's now use this knowledge to create a new page and load the page with a couple of portlets:
Click on the Add option in the Dockbar. Select the Page option from the drop-down.
It will display a textbox with the yellow background in the page navigation.
Add the name of the page here, Collaboration, and click on the tick mark next to the textbox. You should now see the page added to the page navigation.
Click on the Add option from the Dockbar and select More from the drop-down.
Search for the Blogs portlet and Polls Display portlet. Add these portlets to the page.
Try adding the same portlets a second time and see what happens.
You would be able to add another polls display portlet to the page but not another blogs portlet. Can you tell why this happened? If you cannot, revisit the last section. It is related to the portlet instance.