I am just an occasional user of Indesign as may be obvious from my question.
I have a picture that I am using as a background to a flyer. On the screen the picture covers the entire document but when I print the document there is a white border all the way around it. How do I get rid of this. In other words why doesn't the picture print all the way to the edge of the paper.
That is a physical limitition of your printer. Ink can not print to the edge so the gripper can grab the paper, and also so that ink doe s not go off the edge dirty the roller and foul the inside of your printer.
You will have to either print to a larger piece of paper and cut it down.