change xorg video resolution

[freenity]

well this is what xpdyinfo says. Its screen0 section:

screen #0:
  print screen:    no
  dimensions:    1024x768 pixels (342x271 millimeters)
  resolution:    76x72 dots per inch
  depths (7):    16, 1, 4, 8, 15, 24, 32
  root window id:    0x3e
  depth of root window:    16 planes
  number of colormaps:    minimum 1, maximum 1
  default colormap:    0x20
  default number of colormap cells:    64
  preallocated pixels:    black 0, white 65535
  options:    backing-store NO, save-unders NO
  largest cursor:    1024x768
  current input event mask:    0xfa4031
    KeyPressMask             EnterWindowMask          LeaveWindowMask
    KeymapStateMask          StructureNotifyMask      SubstructureNotifyMask
    SubstructureRedirectMask FocusChangeMask          PropertyChangeMask
    ColormapChangeMask
  number of visuals:    4
  default visual id:  0x22
  visual:
    visual id:    0x22
    class:    TrueColor
    depth:    16 planes
    available colormap entries:    64 per subfield
    red, green, blue masks:    0xf800, 0x7e0, 0x1f
    significant bits in color specification:    6 bits
  visual:
    visual id:    0x23
    class:    TrueColor
    depth:    16 planes
    available colormap entries:    64 per subfield
    red, green, blue masks:    0xf800, 0x7e0, 0x1f
    significant bits in color specification:    6 bits
  visual:
    visual id:    0x24
    class:    TrueColor
    depth:    16 planes
    available colormap entries:    64 per subfield
    red, green, blue masks:    0xf800, 0x7e0, 0x1f
    significant bits in color specification:    6 bits
  visual:
    visual id:    0x25
    class:    TrueColor
    depth:    16 planes
    available colormap entries:    64 per subfield
    red, green, blue masks:    0xf800, 0x7e0, 0x1f
    significant bits in color specification:    6 bits


I don't understand well what do you mean by telling that I need a subsection
entry for that depth.
The duplicate section had a 1024x768 configuration before, I changed it for
testing purpose.