how to change background color

A quick look at the links in the More Like This list to the right showed none that applied to Pages (although I'm sure the topic has been discussed here before), so here are the instructions:

Go to the first page of the document (or of the section).

Insert a rectangular Shape.

Make the shape Floating and choose "none" from the Wrap button in the Format bar.

Drag the corner handles to make the shape completely fill the page.

Use the Fill color well to set the colour you want for a background.

Use the Stroke color well to set the shape's border to the same colour.

With the shape still selected, go Arrange > Send Objects to Background.

To use the same background on all pages in this section, go Format > Advanced > Move Object to Section Master.

Regards,

Barry

Which background do you refer to?

Colours in apps

Does Barry answer your question? If not you have to divulge more information like is it in Pages on Macs (which this forum is about) or iPads (which you find here iWork for iOS). Which system version do you have? PAges version?

Which apps do you refer to in your answer?