First, make sure you have admin access by selecting the downward arrow next to your profile:
Enter the admin console and select Settings > Home Page, and enable the home page. Be sure to save the settings.
Now the Overview Page will be enabled on your Jive Community. You can edit the layout and configuration by using the 'Overview Page" link from your profile dropdown in the upper right corner.
Note: In Jive 4 and Jive 5 you could have 3 columns of information, in Jive 6 you only have 2 columns since the navigation sidebar takes up a portion of the page.