HI frainds
Any one tell me how I can get full screen image background in Nokia N72

You cannot get full image in background. Some part will still remain uncovered. Note that resolution of wallpaper for Nokia N72 is 176x144 while actual size of screen is 208x176. So full image cannot be used.

BTW there is one online theme creator http://www.ownskin.com where you can create full sized theme with your wallpapers.