Programming Color Codes
To set a pen color in Logo using RGB values (the amount of red, green, and blue in a color), you can do the following.

Use one of the resources below to find the 3 values for Red, Green, and Blue for your desired color.

Use the setpc command using a list as the input. The list contains the RGB values -- in that order, no commas.
Example:  setpc [138 43 226]

Use values in the RGB column at this website: 
Color Chart

Or use the Google Gadget below. (If you do not see it, refresh your page.)

Color Picker Google Gadget
Adjust the sliders until you have the color that you want.  Then look at the bottom for the RGB values.