html/css trouble

[HollyThirtyFive]

Hi,

I've started teaching myself html/css and have struck a problem! I wanted to create an orange background with white content background in the middle.
However like the jpeg shows the border up until the body main div. (i may be talking gobbledy gook lol I've only been learning a week!)

(there is text in the black boxes but i've blocked it for now as its only draft ramblings!)

My codes are:
css:


html:


I want to make the borders go all the way to the bottom of the page. But can't figure out what needs changing!

Help very much appreciated