You can use the Color chooser to define you own colors.
In the Color Chooser, click Define Custom Colors >>.
The full
color chooser and color customization tools are displayed.
Click one of the free boxes in the Custom Colors area.
The colored area with the cross (in bottom left part of the spectrum in the picture above) represents a color spectrum.
Drag the cross inside the spectrum to instantaneously change the
color in the small box below the spectrum.
The HSL (Hue, Saturation and Luminance) and RGB (Red, Green and
Blue) values vary according to where the cross is located. You can
also enter HSL and RGB values in the boxes provided to suit your
exact color specifications.
HSL (for Hue, Saturation and Luminance) is an alternate model to
RGB model for color specification:
Move the arrow up or down to vary the brightness of the custom
color:
When you are happy with the color, click one of the free boxes in
the Custom Colors area, then Click Add to Custom Colors
to add the newly created color:
Click Apply to apply new color without closing the Color
chooser or click OK to apply the color and close the dialog
box.