Start designing your app in App Creator, where on the left hand side you'll see "Design App."
Primary Theme Color
The primary theme will be the fill color for the header bar, the app background and various other design elements. White text must be legible over this color. Also, feel free to copy+paste the hex code to exactly match your brand colors.
Secondary Theme Color
This color will be used for the save and share buttons and to highlight which section a user is viewing at any given moment. It should be easily visible over a white background.
Displays in the navigation bar (see below) and should be legible over the primary theme color. White works best, and the background must be transparent. The one size requirement is the logo must have a height of 132 pixels.