On the OpenOffice.org – Colors page, you can specify colors to use in OOo documents. You can select a color from a color table, edit an existing color, or define new colors. These colors will then be available in color selection palettes in all components of OOo. You can also define colors within Impress, but those colors will not be available to other components of OOo.
Defining colors to use in color palettes in OOo.