To add a new brand to your account you need to be logged in to your account in a browser (this is not possible from the Fresh Tasks app). Navigate to the Brand Navigation Screen by clicking the Down Arrow next to the current brand in the upper left side of the screen. Select Add Brand, enter the name*, and click Create Brand. You will be added as the first user and brand administrator.
*Note that the brand name must be unique. Otherwise you will be told that the brand already exists.