Good morning hmdnawaz,
To center an element you need three things:
- a valid DocType
- an element with a width
- that elements right/left margins set to auto
In your case, putting a 1,000px width on body may not be the best approach since body's background image is larger than that. Put your width and centering on .page instead.
Mostly you need to clean up some of that CSS!!
There is multiple entries for every element in each linked CSS file along with markup, which defiinetly doesn't belong in there.
See the links about validation in my signature line. Validating will help you a lot!