An activated brand will be visible to your Portal users. You can only have one brand active at a time.
To activate a Portal brand,
From the List of Brands, select the brand you wish to activate.
In the Actions column, click Set as My Active.
On the Activate Portal Brand page, click Set as Active.
Click Yes to confirm activation.
An active brand can be deactivated by selecting another brand to be your active one.
Portal Guide > Account Tab > Manage Portal Brands