Pages- how to remove black background from text copied from internet

How was the text selected to be copied?

Depending on the method used, you may have copied the text itself or may have copied an image of the text as it appears on the screen.

If it is the text, you may be able to use the format inspector to remove or change the background colour, or, if this fails, try pasting it into a blank TextEdit document set to Plain Text,

Regards,

Barry