In a page layout document: Tap on the corner of a page (so that nothing is selected), then tap , tap Background, then do one of the following:
Use a colour or gradient designed to go with the template: Tap Preset, swipe left or right to see all choices, then tap a colour.
Use any colour: Tap Colour, then tap a colour. You can also swipe left to the colour wheel, then drag the slider around the wheel to choose a colour. To preview colours on the page, touch and hold a colour, then drag across the grid. Release your finger to select a colour.
Use a two-colour gradient fill: Tap Gradient, tap Start Colour or End Colour, then tap a colour or swipe left to use the colour wheel. To switch the gradient direction, tap Flip Colour. To change the gradient angle, drag the Angle slider.
Fill with an image: Tap Image, tap Change Image, then choose or take a photo.
When you’re finished, tap anywhere on the page to dismiss the controls.
For more information about the fill options, see Add watermarks and background objects in Pages on iPad